JPH10150395A - Switch circuit, switch and radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a signal pass characteristic for two signal transmission system equal to each other by configuring a diversity switch with two single-pole double-throw switches and arranging the two signal systems in axial symmetry with respect to a prescribed line passing through a common terminal of the t' single-pole double-throw switches. SOLUTION: A diversity switch is a switch of a FET configuration having monolithic circuit integration of the two single-pole double-throw switches as one semiconductor chip, two antenna terminals A1, A2, two reception terminals RE1, RE2 and one transmission terminal (common terminal) TC. The circuit configuration of two signal transmission systems 1, 2 formed to be a semiconductor chip and the chip layout are arranged in axial symmetry by using a straight line M passing through the transmission terminal TC as an axis. Thus, the length of transmission lines 10, 11, 12 is equal to the length of transmission lines 13, 14, 15 with the same structure and the signal pass characteristic of the two signal transmission systems 1, 2 of the diversity switch is made equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit and a switch for switching a transmission path of a high-frequency signal in a time division multiple access (TDMA) system, and a radio device, and more particularly to a switch for diversity in a diversity radio device. About technology.

[0002]

2. Description of the Related Art In a radio apparatus, a diversity system is used to secure stable radio characteristics even in a fading environment. This is based on the fact that two antennas having the same directional characteristics are set apart by a certain interval (generally １ ／ wavelength or more), and that the temporal variation characteristics of the reception level due to fading are different for each antenna. By selecting the antenna having the strong reception level of each antenna, the deterioration of the reception characteristic is reduced.

The effect of the diversity can be obtained not only at the time of reception but also at the time of transmission, and a good result can be obtained by using the antenna selected at the time of transmission at the time of transmission, and the opposing radio does not perform reception diversity. This is particularly effective in some cases.

[0004] The connection between the antenna and the receiving unit and the connection between the antenna and the transmitting unit of a radio apparatus using such a diversity system are as follows.
Switching is performed using a total of three single-pole-double-throw (SPDT) switches.

The single pole double throw switch (SPDT switch) is described in IEICE Technical Report MW83-118, published by the Institute of Electronics, Information and Communication Engineers, pp. 71-78. In this document, as a typical SPDT switch,
GaAs with low voltage operation, low power consumption and excellent integration
SPD composed of sFET (field effect transistor)
A T-switch is described.

The principle of operation of the SPDT switch will be described.

[0007] As shown in FIG.
There are three signal terminals, an antenna terminal ANT, a reception terminal RX, and a transmission terminal TX, and two control terminals VC1 and VC2. ANT is connected to the antenna, RX is connected to the receiving unit (receiver), and TX is connected to the transmitting unit (transmitter).

A field effect transistor 2 (FET2) is incorporated between the reception terminal RX and the antenna terminal ANT via a drain and a source, and the antenna terminal AN
An FET 3 is incorporated between T and the transmission terminal TX via a drain and a source. Also, control terminals VC1, V
C2 is connected to the gate wiring of FET2 and FET3.

The source or the drain of the FET 1 whose one of the source and the drain is grounded to the ground G is connected to the receiving terminal RX side. The gate electrode of the FET1 is connected to the gate wiring of the FET3.

The transmission terminal TX has a source,
The source or the drain of the FET 4 whose one of the drains is grounded to the ground G is connected. The gate electrode of the FET 4 is connected to the gate wiring of the FET 2.

The above FET1, FET2, FET
3, a load resistor R is provided on each gate electrode side of the FET4.

In such an SPDT switch,
As a control bias, a 0 V bias or a negative bias Vcon equal to or lower than the threshold voltage of the FET is applied complementarily to the two control terminals VC1 and VC2. 0V to VC1, VC
When VconV is applied to ANT2, ANT and RX are connected. Conversely, when VconV is applied to VC1 and 0V is applied to VC2, ANT is connected to ANT.
And TX are connected.

FIG. 9 shows a diversity mobile radio apparatus having two antennas, one transmitting section and two receiving sections.
This is a conventional example configured using SPDT switches.
9, 1 is a first antenna, 2 is a second antenna,
3 and 4 switch S between transmission mode and reception mode by time S
The PDT switch 5 transmits and receives the first and second antennas 1 and 2 at the time of transmission.
An SPDT switch for switching 2; 7, a transmitting unit; 6, a first receiving unit; and 8, a second receiving unit.

The high-frequency signals received by the first and second antennas are compared in intensity by first and second receiving units 6 and 8 connected by SPDT switches 3 and 4, respectively. At the time of transmission, the transmitting unit 7 controls the first antenna 1 by the SPDT switch 5 and the SPDT switches 3 and 4.
Alternatively, transmission is performed by being connected to one of the second antennas 2.

For convenience of explanation, a system for switching the connection between the first antenna 1 and the first receiving unit 6 and a connection between the first antenna 1 and the transmitting unit 7 will be referred to as a signal transmission system 1, and a system for switching the second antenna 2 and the second receiving unit. 8, a system that switches the connection between the second antenna 2 and the transmission unit 7 is referred to as a signal transmission system 2.

On the other hand, Japanese Patent Application No. 6-203190 (JP-A-8-70245) discloses a low distortion switch including an SPDT switch. In this document, in order to realize a switch having a low control voltage and a small insertion loss, a transmission signal passing FET and a reception signal passing FET are formed in a plurality of gates, or a cascade connection is employed. A configuration for controlling the capacity ratio is employed.

This document also discloses an F for transmitting a transmission signal.
Inductors are connected in parallel to the ET and received signal passing FETs, and each inductor is selected so as to resonate with the parasitic capacitance between the drain and source when the respective FETs are OFF and the passing frequency, thereby isolating the FETs when the FETs are OFF. It also describes a configuration for improving the translation characteristics.

[0018]

Since the conventional diversity switch uses a total of three SPDT switches, the mounting area becomes large. In addition, the production cost increases due to the large number of parts.

In a conventional diversity mobile radio device incorporating a diversity switch, the output signal from the transmission unit 7 passes through two SPDT switches until it is transmitted to the first antenna 1 or the second antenna 2, so that the loss is reduced. It is necessary to increase the output of the transmission unit 7 by the loss, and there is a problem that power consumption increases.

On the other hand, the inventor of the present invention has proposed a diversity switch which can achieve miniaturization and cost reduction by reducing the number of components and can achieve low power consumption of a diversity mobile radio apparatus. However, the structure shown in FIG. 10 was developed.

That is, the diversity switch shown in FIG. 10 realizes the function of the diversity switch composed of three SPDT switches shown in FIG. 9 with a total of two SPDT switches in order to reduce the loss of the transmission signal. .

Assuming that the conventional SPDT switches shown in FIG. 8 are used as the SPDT switches 3 and 4, A1 and A2 correspond to ANT, RE1 and RE2 correspond to RX, and T
1, T2 corresponds to TX. The transmission line 9 for output from the transmission unit 7 is branched at a branch point Tb in the middle, and the transmission lines 10 and
11 are connected to T1 and T2 of the SPDT switches 3 and 4, respectively.

The length of the transmission lines 10 and 11 is selected to be λ / 4, where λ is the wavelength of the high-frequency signal.

However, it has been clarified by the present inventors that such an SPDT switch causes the following problems.

(1) Since the structure is such that a single SPDT switch is mounted on a substrate, for example, if the frequency of a high-frequency signal is 2 GHz and the relative permittivity of the substrate on which these circuits are mounted is 4, the wavelength is 7.5 cm, 2
It is necessary to provide two lines of less than a few centimeters, which increases the mounting area.

(2) Each SPD from the branch point Tb of the transmission line
It is difficult to provide the transmission lines 10 and 11 having the same length and short length to the transmission end of the T switch from the viewpoint of mounting the SPDT switch.

(3) In the diversity system, received signals are compared and a signal transmission system having a stronger received signal is selected at the time of transmission. Therefore, it is desirable that the two signal transmission systems have the same performance. Suppose signal transmission system 1
Is less inferior to that of the signal transmission system 2, at the time of reception, the signal strength of the second receiver 8 is always higher than that of the first receiver 6 even if the received signal strengths of both antennas are equal. As a result, the strength cannot be properly compared, and the effect of the diversity system cannot be obtained.

That is, this is also true of the conventional diversity switch. However, in the configuration of the diversity switch including two or three SPDT switches in total, the processing accuracy of the transmission line on the board to be mounted can be improved.
Due to the positioning accuracy of the SPDT switch mounting, the length of the transmission line connecting the switches is likely to change, making it difficult to make the same, and causing a difference in inductance.
Deviations are likely to occur in the signal passing characteristics of the two signal transmission systems, particularly in the return loss and the insertion loss.

Further, even if a diversity switch circuit is constituted by SPDT switches of the same type, there is a variation in SPDT switch products, and a deviation easily occurs in the signal passing characteristics of the two signal transmission systems. For example, minimum 0.7d
B, SPDT that guarantees a maximum insertion loss of 1.2 dB
When a switch circuit for diversity is configured using two switches, a maximum of 0.5 dB is required between two signal transmission systems.
The insertion loss deviation occurs.

As described above, when the loss differs depending on the signal transmission system, it is necessary to change the output of the transmission unit by the signal transmission system by the difference of the loss in order to keep the output voltage from the antenna constant during transmission. And transmission control becomes complicated.

An object of the present invention is to provide a switch circuit, a switch, and a radio device in which the signal transmission characteristics of two signal transmission systems are equal.

Another object of the present invention is to provide an integrated switch circuit and a switch.

Another object of the present invention is to provide a switch and a radio device which can achieve a reduction in power consumption.

Another object of the present invention is to provide a switch circuit, a switch, and a wireless device that can achieve miniaturization and cost reduction.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0036]

The following is a brief description of an outline of typical inventions disclosed in the present application.

(1) A signal transmission system 1 having a first antenna terminal, a first reception terminal and a transmission terminal, a signal transmission system 2 having a second antenna terminal, a second reception terminal and a transmission terminal, and a transmission terminal A transmission circuit including a ground circuit, wherein the transmission terminals of the signal transmission system 1, the signal transmission system 2 and the ground circuit are the same shared transmission terminal, and the signal transmission system 1 has a gate electrode connected to a predetermined control terminal. A field effect transistor (FET) for passing a received signal, wherein one of a source electrode and a drain electrode is connected to the first receiving terminal and the other electrode is connected to the first antenna terminal; One of a source electrode and a drain electrode is connected to a predetermined control terminal, the other electrode is connected to the first antenna terminal, and the other electrode is the common transmission terminal. FET for transmission signals pass to be connected
A ground electrode in which a gate electrode is connected to the gate electrode of the transmission signal passing FET, one of a source electrode and a drain electrode is connected to the first reception terminal, and the other electrode is connected to a ground terminal. FET and
In the signal transmission system 2, a gate electrode is connected to a predetermined control terminal, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to the second antenna terminal. FET for receiving signal passage
A transmission signal passing FET having a gate electrode connected to a predetermined control terminal, one of a source electrode and a drain electrode connected to the second antenna terminal, and the other electrode connected to the common transmission terminal. And a gate electrode connected to the gate electrode of the transmission signal passing FET, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to a ground terminal. And a ground circuit in which a gate electrode is connected to a predetermined control terminal, one of a source electrode and a drain electrode is connected to the common transmission terminal, and the other electrode is connected to a ground terminal. FE for
T.

The reception signal passing FET, the transmission signal passing FET, and the grounding FET connected to the common transmission terminal are each constituted by an FET having two or more gate electrodes. A capacitance is provided between the source electrode and the gate electrode near the source electrode in the FET, and a capacitance is provided between the drain electrode and the gate electrode near the drain electrode, and at least the reception signal passing FET is provided. And FET for transmitting signal
An inductor is provided in parallel between the source electrode and the drain electrode.

The switch circuit is formed monolithically on a semiconductor chip. In the semiconductor chip,
The two signal transmission systems are arranged line-symmetrically with respect to a predetermined line passing through the common transmission terminal.

The semiconductor chip is sealed in a sealing body, and the sealing body is provided with a plurality of leads extending inside and outside thereof, and the electrode terminals of the semiconductor chip and the plurality of leads are provided. Are electrically connected by connection means to form a switch.

The switch is connected to two antennas, two receiving units, and one transmitting unit to constitute a wireless device (diversity wireless device).

(2) A signal transmission system 1 having a first antenna terminal, a first reception terminal, and a transmission terminal, and a signal transmission system 2 having a second antenna terminal, a second reception terminal, and a transmission terminal. The transmission terminals of the transmission system 1 and the signal transmission system 2 are switch circuits serving as the same common transmission terminal. The signal transmission system 1 has a gate electrode connected to a predetermined control terminal and one of a source electrode and a drain electrode. And an electrode is connected to the first receiving terminal and the other electrode is connected to the first antenna terminal. A field effect transistor (FET) for passing a received signal, a gate electrode is connected to a predetermined control terminal and a source electrode or A transmission signal passing FET in which one of the drain electrodes is connected to the first antenna terminal and the other electrode is connected to the common transmission terminal; FET for grounding the gate electrode either is one electrode connected to the first reception terminal and the other electrode of the transmitted signal is connected to the gate electrode of the FET for passing a source electrode and a drain electrode connected to the ground terminal
A gate electrode is connected to the gate electrode of the reception signal passing FET, one of a source electrode and a drain electrode is connected to the common transmission terminal, and the other electrode is connected to the ground terminal. FET and
In the signal transmission system 2, a gate electrode is connected to a predetermined control terminal, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to the second antenna terminal. FET for receiving signal passage
A transmission signal passing FET having a gate electrode connected to a predetermined control terminal, one of a source electrode and a drain electrode connected to the second antenna terminal, and the other electrode connected to the common transmission terminal. And a gate electrode connected to the gate electrode of the transmission signal passing FET, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to a ground terminal. And a ground having a gate electrode connected to the gate electrode of the reception signal passing FET, one of a source electrode and a drain electrode connected to the common transmission terminal, and the other electrode connected to the ground terminal. F for
It consists of ET.

(3) In the configuration of the means (1) or (2), the FET for passing the reception signal and the FET for passing the transmission signal are two cascode-connected FETs.
It is composed of

According to the means (1), (a) the diversity switch uses two SPDT switches, so that the number of parts can be reduced, so that the size can be reduced and the manufacturing cost can be reduced. .

That is, the conventional diversity switch has a structure in which three single SPDT switches are mounted on a substrate, so that the size of the switch is large, and the number of components is large, and the assembly work cost for mounting and the like is high, resulting in high cost. .

On the other hand, in the case of the present invention, other circuits including the two SPDT switches are monolithically formed on a single silicon substrate, and predetermined electrode terminals are arranged around the semiconductor chip. With this structure, the diversity switch circuit is small and inexpensive. Also, a diversity switch, which is a semiconductor device in which this semiconductor chip is incorporated and sealed, is smaller and less expensive. Further, the diversity wireless device incorporating the diversity switch also becomes small. As a result, the diversity mobile radio device can be reduced in size and cost,
Handling is also convenient.

Also, in the diversity switch circuit, since there are two SPDT switch circuit portions,
Circuit simplification and miniaturization are also achieved.

(B) In the diversity mobile radio apparatus, the output signal only passes through a single SPDT switch circuit provided between the transmitting section and the first antenna or the second antenna. Since the signal does not pass through the SPDT switches, the loss is reduced, and the output of the transmission unit does not need to be increased. Therefore, in the diversity radio, a diversity switch circuit and a diversity switch that can achieve a reduction in the output of the transmitting unit are also provided.

(C) Since the diversity switch circuit is built in a single semiconductor chip, the transmission line can be shortened. In particular, the transmission line from the transmission terminal to the terminal (drain or source of the FET) of the two SPDT switch circuits (actually, the FET) can be partially shared and shortened. Therefore, the transmission line in the diversity switch circuit, the diversity switch, and the diversity mobile radio device can be shortened, and the transmission loss can be reduced.

(D) Since the wiring patterns of the two signal transmission systems in the semiconductor chip are arranged symmetrically, the signal transmission characteristics of the two signal transmission systems become the same, and an accurate diversity effect can be obtained.

That is, since the conventional diversity switch has a configuration in which three single SPDT switches are combined, the processing accuracy of the transmission line on the substrate on which the SPDT switch is mounted and the positioning accuracy of the SPDT switch mounting require: The length of the transmission line connecting the switches is likely to change, making it difficult to make them the same, and causing a difference in inductance, causing a deviation in the signal passing characteristics of the two signal transmission systems, especially return loss and insertion loss. In the case of the present invention, since the two SPDT switch circuits are formed monolithically on a single semiconductor chip, the signal transmission characteristics of the two signal transmission systems can be the same.

(E) Since the signal transmission characteristics of the two signal transmission systems are the same, transmission control in the diversity mobile radio apparatus becomes easy. In other words, when a deviation (insertion loss deviation) occurs in the signal passing characteristics of the two signal transmission systems, the transmission section is controlled by the signal transmission system by the difference of the loss in order to keep the output voltage from the antenna constant during transmission. Needs to be changed, which complicates the transmission control. In the case of the present invention, the signal transmission characteristics of the two signal transmission systems are the same, so that the transmission control can be simplified.

(F) In the reception signal passing FET and the transmission signal passing FET, the capacitance between the gate electrode and the drain near the drain electrode increases the amplitude of the AC signal generated at the gate electrode near the drain electrode. Let
Prevents the FET from turning on when the signal swings negatively, and inserts a capacitance between the gate electrode near the source electrode and the source to generate AC at the gate electrode near the source electrode.
The signal amplitude is reduced to prevent the FET from turning on when the signal swings positively, thereby improving the signal withstand voltage characteristics. A capacitance is also provided in the FET of the ground circuit to improve signal withstand voltage characteristics.

(G) Inductors are connected in parallel to the reception signal passing FET and the transmission signal passing FET, and each of the inductors resonates at the passing frequency with the parasitic capacitance between the drain and source when the FET is off. In this case, the isolation characteristics at the time of off-state are improved.

According to the means (2), the effects (a) to (e) are exhibited as in the case of the means (1).

According to the means of the above (3), even if the reception signal passing FET and the transmission signal passing FET are constituted by two cascode-connected FETs, the same as in the case of the means (1). The effects (a) to (g) are exhibited.

[0057]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
FIG. 2 is a plan view showing a semiconductor chip constituting a diversity switch, FIG. 2 is a schematic plan view showing a pattern example of a dual gate FET formed on the surface of the semiconductor chip, and FIG. 3 is a diversity switch of the first embodiment. It is a circuit diagram.

The diversity mobile radio apparatus according to the first embodiment has a schematic configuration as shown in FIG. In the diversity switch, two SPDT switches (circuits) and transmission lines 9, 10, and 11 are monolithically integrated on one semiconductor chip 50 as shown in FIG. 1, and two antenna terminals A1, A2 and two Receiving terminals RE1 and RE2
And a FET having one transmission terminal (shared transmission terminal) TC
A switch with a configuration. This eliminates the need for another switch or a transmission line for branching outside, and can reduce the mounting area.

The circuit configuration and the chip layout between the transmitting terminal and the antenna terminal and between the antenna terminal and the receiving terminal of the two signal transmission systems (signal transmission systems 1 and 2) formed on the surface layer of the semiconductor chip 50 are shown in FIG. They are arranged symmetrically about a straight line M passing over the terminal TC. Thereby, the transmission line 10 and the transmission line 11, and the transmission line 12 and the transmission line 1
3. The transmission lines 14 and 15 have the same structure and the same length.

An FET connected between the transmission line 10 and the transmission line 14, a transmission line 11 and a transmission line 15
The FET connected between the transmission lines 12 and 14 has the same structure, and the FET connected between the transmission lines 13 and 15 has the same structure as the FET connected between the transmission lines 13 and 15.
Becomes Therefore, the structure between the transmitting terminal and the antenna terminal through which the signal passes, between the antenna terminal and the receiving terminal becomes the same,
The signal passing characteristics of the two signal transmission systems of the diversity switch can be made equal.

The antenna terminal A1 is connected to the first antenna 1, the antenna terminal A2 is connected to the second antenna 2, the reception terminal RE1 is connected to the first reception unit 6,
The receiving terminal RE2 is connected to the second receiving unit 8, the shared transmitting terminal TC is connected to the transmitting unit 7, and the other terminals are connected to a control terminal device or the like (not shown) to constitute a diversity mobile radio device. You.

The diversity switch of FIG. 6 means not only a circuit and a semiconductor chip but also a diversity switch having a semiconductor device structure.

The semiconductor chip 50 is sealed in a predetermined sealing body to form a semiconductor device 51, and the diversity switch in the form of the semiconductor device 51 is incorporated in the diversity mobile radio device.

As shown in FIGS. 4 and 5, the diversity switch in the form of the semiconductor device 51 has a plurality of external electrodes from both sides of a resin sealing body (package) 52, for example. The lead 53 as a terminal has a protruding shape. The number of leads 53 is, for example, seven on each side, for a total of 14 leads. The lead 53 is a gull-wing type that can be surface-mounted.

A metal support plate 54 is provided in the sealing body 52.
The semiconductor chip 50 is fixed at the center of the upper surface of the support plate 54. The support plate 54 has two leads 53 projecting from both sides thereof. These leads 53 constitute a ground lead (ground lead).

The electrodes of the semiconductor chip 50 and the tips of the leads 53 in the sealing body 52 are electrically conductive wires 5
5 is connected. The ground terminal of the semiconductor chip 50 and the support plate 54 are connected by a conductive wire 55.

Next, a description will be given of the diversity switch circuit and the semiconductor chip 50 in which the circuit is incorporated.

FIG. 3 shows a circuit configuration of the first embodiment. The circuit configuration is symmetric except for the ground circuit 60 on the transmission side, with the straight line M passing over the shared transmission terminal TC as the axis of symmetry. That is, the left side of the straight line M is the signal transmission system 1, and the right side is the signal transmission system 2. Further, as shown in FIG. 1, the pattern of the semiconductor chip 50 incorporating this circuit is symmetric except for the ground circuit 60.

The last digit of each symbol represents the signal transmission system, the left signal transmission system is represented by 1, and the right signal transmission system is represented by 2. If the last two digits are the same, the FE
T indicates the same action and structure. For example, FET11 is FET1 in the signal transmission system 1, and FE
T12 indicates the FET 1 in the signal transmission system 2 and indicates the same FET (in this case, a ground FET).

In the first embodiment, in the signal transmission system 1 and the signal transmission system 2, since the FETs located at the symmetric positions have the same structure, the signal passing characteristics are equal, and the FETs located at the symmetric positions are connected. Since the transmission lines have the same length and the same structure, there is no difference in inductance. Therefore, the signal transmission characteristics of the two signal transmission systems, particularly the return loss and the insertion loss, are characterized in that no deviation occurs.

In the diversity switch circuit of FIG. 10 described above, for example, a minimum of 0.7 dB and a maximum of 1.2 dB are used.
When two single SPDT switches of the same type that guarantee the insertion loss of dB are used, the insertion loss between the two signal transmission systems has a maximum deviation of 0.5 dB. However, in the first embodiment, two signal transmission systems for diversity are integrated on a single semiconductor chip having an area of at most about 2 square mm. Since there is only the influence of internal variation, there is almost no deviation in the signal passing characteristics of the two signal transmission systems.

In the diversity switch circuit of FIG. 10, the SPDT switches 3 and 4 have 5.0 ×
When using a 6.3 mm 8-pin package and connecting with two transmission lines each having a length of less than 2 cm, the mounting area is 2 to 4 square c.
m, but in the first embodiment, the package is set to 5.
The size is 2 × 5.5 mm (14-pin package), and the mounting area can be greatly reduced.

In this case, the insertion loss and the deviation of the isolation between the two signal transmission systems were within 5%, respectively. The maximum deviation of the insertion loss is 0.05
dB, and it can be said that there is almost no deviation in consideration of measurement accuracy.

Next, the diversity switch circuit will be described. This circuit is monolithically formed on a semiconductor chip 50 as shown in FIG.

As shown in FIG. 3, the diversity switch circuit of the first embodiment is roughly divided into first antenna terminals A
1, a signal transmission system 1 having a first reception terminal RE1 and a transmission terminal, a second antenna terminal A2, a second reception terminal RE1.
2 and a signal transmission system 2 having a transmission terminal, and a grounding circuit having a transmission terminal (transmission-side grounding circuit 60). The transmission terminals of the signal transmission system 1, the signal transmission system 2 and the transmission-side grounding circuit 60 are This is a switch circuit that becomes the same shared transmission terminal TC.

The signal transmission system 1 has a gate electrode connected to a predetermined control terminal VC11, and one of a source electrode and a drain electrode connected to the first reception terminal RE.
1 and the other electrode is connected to the first antenna terminal A1.
And a field-effect transistor (FET21) for passing a received signal connected to the power supply.

The gate electrode is connected to a predetermined control terminal VC2.
1, one of a source electrode and a drain electrode is connected to the first antenna terminal A1,
The other electrode has a transmission signal passing FET 31 connected to the common transmission terminal TC.

A gate electrode is connected to the gate electrode of the transmission signal passing FET 31, one of a source electrode and a drain electrode is connected to the first reception terminal RE1, and the other electrode is connected to a ground terminal. It has a grounded FET 11 connected to G1.

The signal transmission system 2 has a gate electrode connected to a predetermined control terminal VC12, and one of a source electrode and a drain electrode connected to the second reception terminal RE12.
2 and the other electrode is connected to the second antenna terminal A2.
And a FET 22 for receiving a signal passing therethrough.

The gate electrode is connected to a predetermined control terminal VC2.
2, one of a source electrode and a drain electrode is connected to the second antenna terminal A2,
The other electrode has a transmission signal passing FET 32 connected to the common transmission terminal TC.

A gate electrode is connected to the gate electrode of the transmission signal passing FET 32, one of a source electrode and a drain electrode is connected to the second reception terminal RE2, and the other electrode is connected to a ground terminal. It has a grounding FET 12 connected to G2.

The transmission-side grounding circuit 60 has a gate electrode connected to a predetermined control terminal VC3, one of a source electrode and a drain electrode connected to the common transmission terminal TC, and the other electrode grounded. It is composed of a grounding FET 4 connected to the terminal G3. In the case of the semiconductor chip 50 shown in FIG. 1, a plurality of ground terminals G3 are provided.
1 and G32.

The receiving signal passing FET 21 and FET
22, FETs 31 and 32 for transmitting a transmission signal and a grounding FET 4 connected to the common transmission terminal TC
Is a FE having two or more gate electrodes.
T: In this embodiment, the device is constituted by a dual-gate FET.

By using a dual-gate FET and dividing the signal voltage for each gate, a diversity switch having a low voltage operation and a high linearity is realized.

A dual gate FET is a single gate F
As compared with the ET, the resistance of the operation layer and the parasitic resistance between the gates are additionally added, and the series parasitic resistance at the time of ON increases, which causes an increase in insertion loss. Therefore, in the first embodiment, a single gate is used for the FETs 11 and 12 that do not significantly contribute to the withstand voltage. For the FETs 11 and 12, FETs with improved withstand voltage may be used.

FIG. 2 shows an example of a pattern of a dual gate FET formed on the surface of the semiconductor chip 50. In FIG. 2, 61 is a first gate, 62 is a second gate, 63 is a source electrode, and 64 is a drain electrode.

Further, load resistors R1 to R12 are provided in the gate wiring portion of each FET, respectively.

On the other hand, the FET 21 for passing the received signal,
FET22 and FET31, FET for transmission signal passage
32 and the transmission side grounding FET 4
Capacitors C1 to C10 are provided between the gate (gate on the source side) and the source, and between the second gate and the drain, to improve signal withstand voltage characteristics.

By providing a capacitor between the second gate and the drain, the amplitude of the AC signal generated at the second gate is increased to prevent the FET from turning on when the signal swings negatively.
By providing a capacitor between the first gate (source side gate) and the source, the amplitude of the AC signal generated at the first gate is reduced, and when the signal swings positively, the FET is prevented from turning on, and the signal withstand voltage is reduced. The characteristics are improved.

In the first embodiment, a dual gate FET is used. However, when an FET having more gate electrodes is used, a gate between a source electrode and a gate electrode near the source electrode and a drain electrode A capacitor may be provided between the gate electrode and the gate electrode near the drain electrode.

On the other hand, in the first embodiment, the reception signal passing FETs 21 and 21 through which the reception and transmission signals pass.
2. Inductors L11, L21, L12 and L22 are connected in parallel with the transmission signal passing FETs 31 and 32. By selecting each inductor so as to resonate with the parasitic capacitance between the drain and source when the FET is off and the passing frequency, the isolation characteristics when off are improved.

Next, the operation principle of the diversity switch according to the first embodiment will be described with reference to FIG.

The antenna terminals A1 to F of the signal transmission system 1
To pass a signal to the receiving terminal RE1 after passing through the ET21, 0 V is applied to the control terminal VC11 and the control terminal VC2
VconV is added to 1, and 0V or VconV is applied to the other three control terminals. Since the signal transmission system 2 is not used, the control terminals VC12, VC22, and VC3 may be either 0V or VconV.
VconV is desirable for the control terminal VC12 and the control terminal VC22, and 0 V is desirable for the control terminal VC3 in order to prevent mixing of unnecessary signals.

The antenna terminals A2 to F of the signal transmission system 2
To receive a signal at the receiving terminal RE2 through the ET22, 0 V is applied to the control terminal VC12, and the control terminal VC2
VconV is added to 2 and 0V or VconV is applied to the other three control terminals. Since the signal transmission system 1 is not used, the control terminals VC11, VC21, and VC3 may be either 0V or VconV.
VconV is desirable for the control terminal VC11 and the control terminal VC21, and 0V is desirable for the control terminal VC3 in order to prevent mixing of unnecessary signals.

Of course, terminal A1, terminal RE1, terminal A
2 and the terminal RE2 can be simultaneously connected. In this case, 0V is applied to the terminals VC11 and VC12, VconV is applied to the control terminals VC21 and VC22, and 0V or VconV is applied to the control terminal VC3. In order to prevent mixing of an unnecessary signal from the common transmission terminal TC, the control terminal VC3 is desirably 0V.

[0097] From the common transmission terminals TC to F of the signal transmission system 1
To transmit a signal to the antenna terminal A1 through the ET31, 0 V is applied to the control terminal VC21 and the control terminal VC1 is applied.
11, VconV is applied to the control terminal VC22, and 0V or VconV is applied to the control terminal VC12. In order to prevent mixing of an unnecessary signal from the receiving terminal RE2, it is desirable that the control terminal VC12 be set to VconV.

[0098] From the common transmission terminal TC of the signal transmission system 2 to F
To transmit a signal to the antenna terminal A2 through the ET 32, 0 V is applied to the control terminal VC22 and the control terminal VC
12. VconV is applied to the control terminal VC21, and 0V or VconV is applied to the control terminal VC11. In order to prevent mixing of an unnecessary signal from the receiving terminal RE1, it is desirable that the control terminal VC11 be set to VconV.

FET11, FET12 and FET4
Are grounding FETs at the receiving and transmitting ends, respectively, and are terminated by the on-resistance of the grounding FET at the transmitting end during reception, and terminated by the on-resistance of the grounding FET at the receiving end during transmission. If these are not provided, the terminals are open and the input wave is totally reflected, which may cause inconvenience for the wireless device. Therefore, these FETs are connected. The transmission lines used for these FETs and the connection affect the signal passing characteristics of the switch, particularly the return loss and the insertion loss. Therefore, the circuit configuration and the chip layout of this portion also take a line around the straight line M passing over the terminal TC. Must be symmetric.

In general, in a radio device, a transmission signal has a medium to high power, and in a switch constituted by an FET, transmission power capable of maintaining linearity is limited mainly by the signal withstand voltage of the FET.

In the case of the first embodiment, when the common transmission terminal TC and the antenna terminal A2 are connected and a large signal is transmitted from the common transmission terminal TC, the drains of the FET 22 and the FET 4 constituting the signal transmission system 2 are connected. Obviously, a large voltage is applied to the (or source) end, but a large voltage is also applied to the drain (or source) end of the FET 31 constituting the signal transmission system 1. This is caused by connecting two SPDT switches to form a diversity switch.

Similarly, when the common transmission terminal TC and the antenna terminal A1 are connected, a large voltage is applied to the drain (or source) terminals of the FET21, FET4 and FET32. Therefore, in the first embodiment, the FET 21 and the FE
A dual-gate FET is used for T31, FET22, FET32, and FET4, and a signal voltage is divided for each gate, thereby realizing a diversity switch having low voltage operation and high linearity.

The dual gate FET is a single gate F
As compared with the ET, the resistance of the operation layer and the parasitic resistance between the gates are additionally added, and the series parasitic resistance at the time of ON increases, which causes an increase in insertion loss. For this reason, in the first embodiment, a single gate is used for the FETs 11 and 12 that do not significantly contribute to the signal voltage resistance. Of course, an FET with improved signal voltage resistance may be used.

As a method of dividing a signal voltage, a dual gate FET is used in the first embodiment.
FETs and FEs with two or more gate electrodes
It is effective to replace T with a cascode-connected FET.

The diversity switch circuit, the diversity switch, and the diversity wireless device of the first embodiment have the following advantages.

(1) The conventional diversity switch has a structure in which three single SPDT switches are mounted on a board. The diversity switch of the first embodiment has two SDT switches.
Since the PDT switch is used, the number of parts can be reduced, so that the size can be reduced and the manufacturing cost can be reduced.

In particular, in the case of the first embodiment, the two S
Since the PDT switch and other circuits are monolithically formed on a single silicon substrate, and the predetermined electrode terminals are arranged around the semiconductor chip, the diversity switch circuit is small and inexpensive. become. Also, a diversity switch, which is a semiconductor device incorporating this semiconductor chip, becomes smaller and less expensive. Further, the diversity wireless device incorporating the diversity switch also becomes small. As a result, the size and cost of the diversity mobile radio apparatus can be reduced, and the handling becomes convenient.

(2) Since the grounding FETs on the transmission side of the signal transmission system 1 and the signal transmission system 2 are integrated into one, the chip area can be reduced.

(3) In the conventional diversity mobile radio apparatus, since the output signal from the transmitting unit passes through two SPDT switches before being transmitted to the first antenna or the second antenna, the loss is large, and the loss is large. Although it was necessary to increase the output of the transmission unit, in the case of the diversity mobile radio apparatus according to the first embodiment, the SP formed monolithically was used.
As one of the DT switches, transmission loss can be reduced, so that it is not necessary to increase the output of the transmission unit, and power consumption can be reduced.

(4) Since the diversity switch circuit is symmetrically incorporated into a single semiconductor chip,
Since the length and shape of the transmission line between the passive element and the active element in the semiconductor chip are equal between the two signal transmission systems, the deviation of the inductance component hardly occurs, and the deviation of the signal passing characteristic hardly occurs.

That is, since the conventional diversity switch has a configuration in which three single SPDT switches are combined, the processing accuracy of the transmission line on the substrate on which the SPDT switch is mounted and the positioning accuracy of the SPDT switch mounting are different. The length of the transmission line connecting the switches is likely to change, making it difficult to make them the same, and causing a difference in inductance, causing a deviation in the signal passing characteristics of the two signal transmission systems, especially return loss and insertion loss. In the case of the first embodiment, since the two SPDT switch circuits are symmetrically assembled on a single semiconductor chip, the signal transmission characteristics of the two signal transmission systems can be the same.

Thus, an accurate diversity effect can be obtained.

(5) As a result of incorporating the diversity switch circuit monolithically in a single semiconductor chip, the transmission line can be shortened. In particular, the transmission line from the transmission terminal to the terminal (drain or source of the FET) of the two SPDT switch circuits (actually, the FET) can be partially shared and shortened.

(6) If there is a deviation (insertion loss deviation) in the signal passing characteristics of the two signal transmission systems, the signal transmission is performed by the difference of the loss to keep the output voltage from the antenna constant during transmission. Although it is necessary to change the output of the transmission unit depending on the system, the transmission control becomes complicated. However, according to the diversity mobile radio apparatus of the first embodiment, the transmission control becomes easy (simplified).

(7) In a reception signal passing FET and a transmission signal passing FET, the capacitance between the gate electrode and the drain near the drain electrode increases the AC signal amplitude generated at the gate electrode near the drain electrode. Let
Prevents the FET from turning on when the signal swings negatively, and inserts a capacitance between the gate electrode near the source electrode and the source to generate AC at the gate electrode near the source electrode.
The signal amplitude is reduced to prevent the FET from turning on when the signal swings positively, thereby improving the signal withstand voltage characteristics. A capacitance is also provided in the FET of the ground circuit to improve signal withstand voltage characteristics.

(8) An inductor is connected in parallel to the reception signal passing FET and the transmission signal passing FET, and each inductor is resonated at the passing frequency with the parasitic capacitance between the drain and source when the FET is off. In this case, the isolation characteristics at the time of off-state are improved.

(9) A diversity switch was assembled in a 14-pin package (5.2 × 5.5 mm) and prototyped. As a result, the insertion loss and isolation deviation between the two signal transmission systems were within 5%, respectively. . Among them, the maximum value of the deviation of the insertion loss is 0.05 dB, and it can be said that there is almost no deviation in consideration of the measurement accuracy.

(10) Since the influence of the layout can be estimated equally for both signal transmission systems, the switch design can be simplified.

(Embodiment 2) FIG. 7 shows Embodiment 2 of the present invention.
FIG. In the first embodiment, the ground circuit 60 on the transmission side is shared by the signal transmission system 1 and the signal transmission system 2. However, in the second embodiment, the ground circuit 60 on the transmission side is removed, and This is an example in which the transmission system 1 and the signal transmission system 2 are provided with independent ground circuits on the transmission side.

That is, in the signal transmission system 1, a gate electrode is connected to the gate electrode of the reception signal passing FET 21 and one of a source electrode and a drain electrode is connected to the common transmission terminal TC. FET 41 for grounding whose other electrode is connected to ground terminal G6
In the signal transmission system 2, a gate electrode is connected to a gate electrode of the reception signal passing FET 22;
One of a source electrode and a drain electrode is connected to the common transmission terminal TC, and the other electrode is provided with a ground FET 42 connected to the ground terminal G7.

In the second embodiment, the FE for passing the received signal
T21, FET22 and transmission signal transmission FET3
1, FET32 and grounding FET41, FET4
2 is a dual gate FET. However, unlike the first embodiment, no capacitor for improving the signal withstand voltage characteristic or an inductor for improving the isolation characteristic at the time of OFF is provided.

The other circuit parts are the same as in the first embodiment.

In the diversity switch circuit shown in FIG. 10, the SPDT switches 3 and 4 have 5.0 ×
When using a 6.3 mm 8-pin package and connecting with two transmission lines each having a length of less than 2 cm, the mounting area is 2 to 4 square c.
m, but in the first embodiment, 2
Even if a double size 10.0 × 6.3 mm 16-pin package is used, the mounting area will be at most 1 cm 2, and
Can be reduced to 1/2.

Next, the operation principle of the diversity switch according to the second embodiment will be described.

The antenna terminals A1 to F of the signal transmission system 1
To pass a signal to the receiving terminal RE1 after passing through the ET21, 0 V is applied to the control terminal VC11 and the control terminal VC2
VconV is added to 1 and 0V or VconV is applied to the other two control terminals (preferably VconV).

The antenna terminals A2 to F of the signal transmission system 2
To receive a signal at the receiving terminal RE2 through the ET22, 0 V is applied to the control terminal VC12, and the control terminal VC2
2, VconV is applied to the other two control terminals, and 0V or VconV is applied (preferably VconV). Of course, the antenna terminal A1 and the receiving terminal RE1,
The antenna terminal A2 and the receiving terminal RE2 can be connected simultaneously, in which case the control terminal VC11 and the control terminal V
0V is applied to C12, and Vcon is connected to the remaining two control terminals.
V is applied.

From the common transmission terminals TC to F of the signal transmission system 1
To transmit a signal to the antenna terminal A1 through the ET31, 0V is applied to the control terminal VC21, and VconV is applied to the other control terminals.

The common transmission terminals TC to F of the signal transmission system 2
To transmit a signal to the antenna terminal A2 through the ET 32, 0V is applied to the control terminal VC22, and VconV is applied to the other control terminals.

In the second embodiment, since the grounding FETs of the signal transmission system 1 and the signal transmission system 2 are separated, the area for the grounding FET is slightly larger than that of the first embodiment. I hate it.

That is, in the second embodiment, the transmission terminal is grounded by the FET 41 when the signal transmission system 1 is received, and the transmission terminal is grounded by the FET 42 when the signal transmission system 2 is received. However, the FET 41 and the FET 42 overlap as a function of grounding the transmission terminal during reception. Therefore, in the case of the first embodiment, since the FETs for grounding the transmission terminals are combined into one, the chip area can be reduced.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.

[0132]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) Since the diversity switch of the present invention does not incorporate a single SPDT switch as in the prior art, but also incorporates other circuits including the SPDT switch circuit into a single semiconductor chip in a monolithic manner. In addition, other switches and transmission lines for branching are not required, so that the number of parts can be reduced and the size can be reduced.

(2) Diversity switch (circuit)
Since the number of SPDT switches is reduced from three in the prior art to two, the circuit can be simplified and the circuit area can be reduced.

(3) A semiconductor device (diversity switch) in which a semiconductor chip having a diversity switch circuit configured in a sealed body is also reduced in size.

(4) Therefore, the diversity mobile radio device incorporating the semiconductor device is also reduced in size. As a result, the diversity mobile radio device can be reduced in size and cost,
Handling is also convenient.

(5) The transmission line can be shortened by making the diversity switch circuit monolithic.

(6) Since the two signal transmission systems in the diversity switch are formed symmetrically on a single semiconductor chip, the transmission line structures of the two signal transmission systems are the same, and the signal transmission characteristics of the two systems are the same. There is almost no deviation, and an excellent diversity effect can be obtained.

(7) According to (6), since there is no deviation (insertion loss deviation) in the signal passing characteristics of the two signal transmission systems, control for keeping the output voltages of the two signal transmission systems constant is also performed. This is unnecessary, and the transmission control circuit in the diversity mobile radio apparatus can be simplified.

(8) In the conventional diversity mobile radio apparatus, since the output signal from the transmitting unit passes through two SPDT switches before being transmitted to the first antenna or the second antenna, the loss is large, and the loss is large. Although it was necessary to increase the output of the transmission unit, in the case of the diversity mobile radio apparatus of the present invention, there is only one SPDT switch, and it is not necessary to increase the output of the transmission unit because transmission loss can be reduced. Power consumption can be reduced.

(9) Since the grounding FETs on the transmission side of the signal transmission system 1 and the signal transmission system 2 are integrated into one, the chip area can be further reduced.

(10) Since capacitance is provided between one of the drain or source electrodes and the first gate and between the other electrode and the second gate of the FET for receiving / transmitting a signal and for grounding, the resistance is high. The signal voltage characteristics can be improved.

(11) Inductors are connected in parallel to the reception / transmission signal passing FETs, and each inductor is selected so as to resonate with the parasitic capacitance between the drain and source when the respective FETs are off and the passing frequency. Therefore, the isolation characteristics in the off state can be improved.

(12) According to the above (1) to (11), it is possible to provide a highly reliable diversity switch circuit, a diversity switch, and a diversity mobile radio device (diversity radio device).

[Brief description of the drawings]

FIG. 1 is a plan view showing a semiconductor chip constituting a switch circuit according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing a pattern example of a dual gate FET formed on the surface of the semiconductor chip of the first embodiment.

FIG. 3 is a switch circuit diagram of the first embodiment.

FIG. 4 is a plan view showing the switch according to the first embodiment.

FIG. 5 is a cross-sectional view illustrating the switch according to the first embodiment.

FIG. 6 is a block diagram of a wireless device incorporating the switch of the first embodiment.

FIG. 7 is a switch circuit diagram according to a second embodiment of the present invention.

FIG. 8 is a circuit diagram showing a conventional SPDT switch.

FIG. 9 is a block diagram of a wireless device incorporating a conventional diversity switch.

FIG. 10 is a block diagram of a wireless device incorporating a diversity switch developed by the present inventors.

[Explanation of symbols]

1 ... first antenna, 2 ... second antenna, 3, 4, 5 ... S
PDT switch (single-pole double-throw switch), 6 first receiving unit, 7 transmitting unit, 8 second receiving unit, 9 transmission line for output, 10, 11, 12, 13, 14, 15, 15 transmission line ,
50 semiconductor chip, 51 semiconductor device, 52 sealing body, 53 lead, 54 support plate, 55 wire, 60
... Ground circuit on the transmission side, 61... First gate, 62... Second gate, 63... Source electrode, 64.
T, A1, A2: antenna terminals, C1 to C10: capacitance,
FET1, FET2, FET3, FET4, FET1
1, FET12, FET21, FET22, FET3
1, FET32, FET41, FET42 ... field effect transistor, L11, L21, L12, L22 ... inductor, RX, RE1, RE2 ... reception terminal, R1 to R12
... Resistance, TX, T1, T2, TC ... Transmission terminal, VC1,
VC2, VC3, VC11, VC12, VC21, VC
22 ... Control terminal.

Claims (8)

[Claims] A signal transmission system having a first antenna terminal, a first reception terminal, and a transmission terminal; and a signal transmission system having a second antenna terminal, a second reception terminal, and a transmission terminal. System 1 and signal transmission system 2
The signal transmission system 1 has a gate electrode connected to a predetermined control terminal, and one of a source electrode and a drain electrode connected to the first reception terminal. A field effect transistor (FET) for passing a received signal, the other electrode being connected to the first antenna terminal, and one of a source electrode and a drain electrode having a gate electrode connected to a predetermined control terminal Are connected to the first antenna terminal, and the other electrode is connected to the common transmission terminal. A transmission signal passing FET, and a gate electrode is connected to a gate electrode of the transmission signal passing FET and a source electrode or a drain electrode. One of the electrodes is connected to the first receiving terminal and the other electrode is connected to the ground terminal; And a grounding FET connected to the gate electrode of the reception signal passing FET, one of a source electrode and a drain electrode is connected to the common transmission terminal, and the other electrode is connected to the ground terminal. In the signal transmission system 2, a gate electrode is connected to a predetermined control terminal, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to the second antenna terminal. FET for passing the received signal
A transmission signal passing FET having a gate electrode connected to a predetermined control terminal, one of a source electrode and a drain electrode connected to the second antenna terminal, and the other electrode connected to the common transmission terminal. And a gate electrode connected to the gate electrode of the transmission signal passing FET, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to a ground terminal. And a ground having a gate electrode connected to the gate electrode of the reception signal passing FET, one of a source electrode and a drain electrode connected to the common transmission terminal, and the other electrode connected to the ground terminal. F for
A switch circuit comprising an ET. 2. A signal transmission system 1 having a first antenna terminal, a first reception terminal and a transmission terminal, a signal transmission system 2 having a second antenna terminal, a second reception terminal and a transmission terminal, and a ground having a transmission terminal. And a transmission circuit of the signal transmission system 1, the signal transmission system 2, and the ground circuit. The transmission terminal of the signal transmission system 1 has a gate electrode connected to a predetermined control terminal. One of a source electrode and a drain electrode is connected to the first receiving terminal, and the other electrode is connected to the first antenna terminal. One of a source electrode and a drain electrode is connected to the first antenna terminal, and the other electrode is connected to the common transmission terminal. A transmission signal passing FET, and a gate electrode connected to the transmission signal passing FET gate electrode, one of a source electrode and a drain electrode is connected to the first reception terminal, and the other electrode is connected to the transmission signal passing FET. A grounding FET connected to a ground terminal, wherein the signal transmission system 2 has a gate electrode connected to a predetermined control terminal, and one of a source electrode and a drain electrode connected to the second reception terminal. A FET for passing a received signal, the other electrode of which is connected to the second antenna terminal
A transmission signal passing FET having a gate electrode connected to a predetermined control terminal, one of a source electrode and a drain electrode connected to the second antenna terminal, and the other electrode connected to the common transmission terminal. And a gate electrode connected to the gate electrode of the transmission signal passing FET, one of a source electrode and a drain electrode is connected to the second reception terminal, and the other electrode is connected to a ground terminal. The grounding circuit has a gate electrode connected to a predetermined control terminal, one of a source electrode and a drain electrode connected to the common transmission terminal, and the other electrode connected to a ground terminal. A switch circuit comprising a grounding FET. 3. The FET for passing a reception signal, the FET for passing a transmission signal, and the FET for grounding connected to the common transmission terminal are each constituted by an FET having two or more gate electrodes. In the FET, a capacitance is provided between the source electrode and the gate electrode near the source electrode, and a capacitance is provided between the drain electrode and the gate electrode near the drain electrode. FET and FE for transmitting signal
3. The switch circuit according to claim 1, wherein an inductor is provided in parallel between the source electrode and the drain electrode of T. 4. The cascode-connected two FETs for passing the reception signal FET and the transmission signal FET.
The switch circuit according to claim 2, wherein the switch circuit comprises: 5. The switch circuit according to claim 1, wherein the switch circuit is formed monolithically on a semiconductor chip. 6. The switch circuit according to claim 5, wherein in the semiconductor chip, the two signal transmission systems are arranged line-symmetrically with respect to a predetermined line passing through the common transmission terminal. 7. The semiconductor chip according to claim 5 or 6, wherein the semiconductor chip is sealed in a sealing body, and a plurality of leads extending inside and outside the sealing chip are provided on the sealing body. A switch comprising an electrode terminal and said plurality of leads electrically connected by connection means. 8. A wireless device comprising two antennas, two receiving units, and one transmitting unit connected to the switch circuit according to claim 1.