JPH1093471A - Signal changeover switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the switching performance in a low voltage operating state of a switching semiconductor element. SOLUTION: In the signal changeover switch 11 that is provided with a switch circuit 12 employing semiconductor elements Q1 -Q4 for switching elements and a plurality of input output terminals ANT, RX, TX and in which the input output terminals ANT, RX, TX are connected/disconnected by the switch circuit 12, impedance conversion circuits M-M3 are provided between the input output terminals ANT, RX, TX and the switch circuit 12. Then an impedance ZSW, when viewing the impedance conversion circuits M1-M3 from the switch circuit 12 is set smaller than an impedance ZO when viewing an external circuit from the input output terminals ANT, RX, TX.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a signal changeover switch. For example, the present invention relates to a high-frequency signal changeover switch used for switching transmission and reception of a mobile phone.

[0002]

[Prior art]

(First Conventional Example) FIG. 1 is a circuit diagram showing a conventional high frequency signal changeover switch 1 used for switching transmission and reception of a portable telephone. Generally, this type of circuit is SPDT
(Single-Pole-Dual-Throw) switch.

The SPDT switch has, as input / output terminals, an ANT terminal (indicated by ANT in the figure) to which a transmitting / receiving antenna is connected, and a TX terminal to which a transmitting power amplifier is connected.
It has a terminal (indicated by TX in the figure) and an RX terminal (indicated by RX in the figure) to which a low-noise amplifier for reception is connected.

The signal changeover switch 1 has four switching semiconductor elements (hereinafter referred to as switching elements) Q _{1 to} Q ₄ , and a GaAs MESFET (GaAs Metal-Semiconducto) is used as a switching element.
r FET) is used. Between ANT terminal -RX terminal, the source and drain of the switching element Q ₁ is connected in series, RX terminal - ground (hereinafter, referred to as GND) between the source and drain of the switching element Q ₂ in series is connected to, between ANT terminal -TX terminal, the source and drain of the switching element Q ₃ are connected in series, between and GND TX terminal, the switching element Q
₄ source / drain are connected in series.

The gates of the switching elements Q _{1 to} Q ₄ are connected to control voltage terminals via resistors R _{1 to} R ₄ , respectively. V _{1 to} V ₄ are the switching elements Q ₁ to
A control voltage applied to the gate of Q ₄ (gate bias V _GB). Each switching element Q ₁ to Q ₄ applies a pinch-off voltage V _P or more voltage V _ON to the gate (V ₁
~V ₄ ≧ V _ON) becomes ON (conductive) state by, conversely, the gate to apply a voltage less than V _OFF pinch-off voltage _{V P (V 1 ~V 4 ≦} V OFF) OFF by (blocked) state Becomes

When transmitting signals through the signal changeover switch 1, the control voltages V ₁ and V ₄ of the switching elements Q ₁ and Q ₄ are _{turned off} , and the switching elements Q ₂ and Q ₄ are _{turned off.
3} of the control voltage V _2, V ₃ when the V _ON, ANT terminal -R
X terminal is OFF, and ANT terminal-TX terminal is O
N, and the transmission signal is output from the transmission-side power amplifier to the antenna.

When receiving the signal through the signal changeover switch 1, the control voltages V ₂ and V ₃ of the switching elements Q ₂ and Q ₃ are _{turned off} , and the control voltage V _{1 of the} switching elements Q ₁ and Q ₄ is _{turned off.} , when the V ₄ to V _oN, between the ANT terminal -TX terminal becomes OFF, between the ANT terminal -RX terminal turns oN, the received signal to a receiver side of the low-noise amplifier from the antenna is input.

[0008] The switching element Q ₂ between and GND RX terminals are turned ON when the switching element Q ₁ is is OFF state, RX terminal side through OFF capacitance of the switching element Q ₁ which is in the OFF state By reducing the signal power leaked to the GND to GND, there is an effect of improving the isolation characteristics of the RX terminal. Similarly, T
Switching element Q ₄ between and GND X terminals, ON when the switching element Q ₃ is in the OFF state
And the switching element Q _{3 in the} OFF state.
By reducing the signal power leaked to the TX terminal side through the OFF capacitance to GND, there is an effect of improving the isolation characteristics of the TX terminal.

FIG. 2 shows a switching element (GaAs M).
ESFET) represents the characteristics of the Q ₁ to Q _4, further, OFF
FIG. 7 is a diagram illustrating a signal voltage waveform applied between the gate and the source of the switching element in the ON state and the switching element in the ON state, wherein the horizontal axis indicates the gate-source voltage V _GS ,
The vertical axis indicates the drain current _IDS . The switching element Q ₁ to Q ₄ are depletion type, I _DSS
The saturation drain current, V _TH is threshold voltage of the gate forward current when the gate-source voltage V _GS = 0, V _P
Pinch-off voltage, I _Fmax is the saturation drain current when the rising voltage V _TH of the gate forward direction current is applied, V
_B is a gate reverse breakdown voltage. For example, the pinch-off voltage is _{V P1 = V P2 = V P3} = V P4 = -1.5V, the control voltage of the switching element _{Q 1 ~Q 4 V ON = 0V} , V OFF
= -3 V, the impedance seen an external circuit from the signal changeover switch is a Z ₀ = 50 [Omega, the amplitude of the largest voltage peak which can be input to the switching element Q ₁ to Q ₄ of the ON state is 3V, and the linear maximum transmission Possible power is 90mW
(19.5 dBm).

Thus, in the conventional high-frequency signal changeover switch 1, the signal voltage ΔV _GS propagating between the ANT terminal and the RX terminal or the TX terminal changes the gate bias V _{GB of} each of the switching elements Q _{1 to} Q ₄ ( V _ON or V _OFF ), and is superimposed on the gate-source voltage V _GS .
When a high power signal is input from the TX terminal during transmission,
The gate-source voltage V _GS is equal to the switching element Q ₁ ~
It reaches the pinch-off voltage V _P of Q _4. At this time, the switching element Q ₃ is supposed at the time of transmission is in the ON state, since the gate-source voltage _{V GS (= V ON + ΔV} GS) temporarily becomes the OFF state each time equal to or less than the pinch-off voltage V _P Then, the transmission power waveform is clipped to cause waveform distortion. That is, when a high-power signal is input from the TX terminal during transmission, the distortion characteristics of the switching element deteriorate.

When a high-power signal is input from the TX terminal, the switching element Q ₁ , which is supposed to be in the OFF state, applies the gate-source voltage V _GS (= V _OFF + ΔV).
Temporarily ON _every time _GS) is greater than or equal to the pinch-off voltage V _P
State, a part of the transmission power leaks to the RX terminal,
The isolation of the X terminal deteriorates.

Furthermore, when a signal of a large power is input from the TX terminal, the switching element Q ₄ which should be OFF state, each gate-source voltage V _GS is equal to or higher than the pinch-off voltage V _P Since it is temporarily turned on, a part of the transmission power drops to GND, and the insertion loss increases.

In the present situation, there is a demand to make the power supply voltage of the high-frequency circuit as small as possible. However, when performing a low-voltage operation for controlling the switching element by the low-voltage power supply, the control voltages V _ON and V _OFF and the pinch-off are required. since the difference between the voltage V _P is reduced, degradation in switching performance due to signal a large voltage to the switching element flows becomes more pronounced, linear maximum transmittable power is reduced. Therefore, it is not practical to deal with the above problem by using a switching element for high power and increasing the power supply voltage.

(Second conventional example) In order to perform high-power signal switching satisfactorily with a low-voltage power supply, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. Hei.
A high-frequency switch circuit using various kinds of switching elements is disclosed. First To apply the signal switching switch 1 of the conventional example, a pinch-off voltage V _P2, V _P3 of the switching element Q _2, Q ₃ to be the ON state at the time of transmission, elements for other switching Q _1, Q ₄ Pinch-off voltage V _P1 , V
_It is better to set lower than _P4 .

For example, V _P1 = V _P4 = −0.8 V, V _P2 =
V _P3 = −2.2 V, and control voltages V _ON = 0 V, V _OFF =
-3 V, the signal when the impedance viewed from the changeover switch the external circuit and Z ₀ = 50 [Omega, the amplitude of the largest voltage peak which can be input to the switching element Q ₃ to be the ON state at the time of transmission 4.4V, and the linear time of transmission The maximum transmittable power increases to about 200 mW (23 dBm).

However, when the conventional high-frequency switch circuit is mounted on a semiconductor integrated circuit, the switching elements having different pinch-off voltages must be formed on the same wafer, which complicates the process and increases the cost. However, there is a problem that the yield is reduced.

(Third conventional example) FIG.
Signal switch 2 disclosed in Japanese Patent No. 4506
FIG. In this signal changeover switch 2, switching elements are connected in multiple stages. In this method, for example, the first conventional signal changeover switch 1
In addition to the switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ , the switching elements Q ₁ ′, Q ₂ ′, Q 4
₃ ', Q _4' may be connected to. Thereby, each switching element Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₁ ′, Q ₂ ′,
The amplitude of the voltage wave superimposed between the gate and source of Q ₃ ′ and Q ₄ ′ is half that of the single-stage configuration, and it is possible to increase the linear maximum transmittable power without increasing the power supply voltage. Has become.

For example, the same pinch-off voltage V _P = −1.5 V, control voltage V _ON = 0 V, V _OFF = − as in the first conventional example.
Using a switching element set at 3 V, the impedance of the external circuit viewed from the signal changeover switch as Z ₀ =
Assuming 50Ω, the amplitude of the maximum voltage wave that can be input is doubled to 6 V, and the linear maximum transmittable power at the time of transmission is 36
It increases to about 0 mW (25.6 dBm).

However, the signal changeover switch 2
, The number of switching elements is required twice,
When mounted on a semiconductor integrated circuit, there is a problem that the element area is doubled, the chip area is increased, and the cost is increased.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to increase the linear maximum transmittable power without increasing the power supply voltage and to achieve switching. And to improve the switching performance of the device.

[0021]

DISCLOSURE OF THE INVENTION A signal switching switch according to a first aspect of the present invention includes a switch circuit in which a semiconductor element is used as a switching element, and a plurality of input / output terminals, and the input / output terminals are connected to each other by the switch circuit. In the signal changeover switch for separating or disconnecting, an impedance conversion circuit is provided between the input / output terminal and the switch circuit, and the impedance when the impedance conversion circuit is viewed from the switch circuit is viewed from the input / output terminal to the external circuit. It is characterized by being smaller than the impedance. Here, the input / output terminal refers to an input terminal, an output terminal, or an input / output shared terminal.

In the signal changeover switch according to the first aspect, since the impedance seen from the switch circuit to the impedance conversion circuit is smaller than the impedance seen from the input / output terminal to the external circuit, the impedance conversion circuit is provided. Accordingly, the amplitude of the voltage wave of the signal power propagating inside the switch circuit decreases. That is, the maximum transmittable power of the signal changeover switch increases without increasing the power supply voltage.

As described above, since the maximum transmittable power of the signal changeover switch is increased without increasing the number of semiconductor elements, it can be manufactured at low cost, and the element area does not increase when mounted on a semiconductor integrated circuit. Furthermore, since it is not necessary to use different types of semiconductor elements having different pinch-off voltages, a switch circuit can be formed in the semiconductor integrated circuit at low cost, which complicates the semiconductor integrated circuit manufacturing process and lowers the yield. Nothing to do.

Also, the switching performance of the semiconductor element (distortion characteristics such as clipping of the signal waveform, insertion loss due to the temporary switching of the semiconductor element and leakage of the signal to GND, isolation between the transmission side and the reception side) Characteristic) is improved, and the semiconductor element can be stably operated with a low-voltage power supply. That is, since the amplitude of the voltage wave superimposed on the gate-source voltage around the control voltage of the semiconductor element becomes small, the switching state of each semiconductor element is kept stable even when a high-power signal is input. And the signal changeover switch can be stably operated with a low-voltage power supply.

Further, when the semiconductor device is turned off, the gate
It is possible to prevent the semiconductor element from being damaged by the source-to-source voltage reaching the gate reverse breakdown voltage and to turn on the semiconductor element.
Sometimes, it is possible to prevent the gate-source voltage from reaching the rising voltage of the gate forward current, causing a large gate current to flow and deteriorating the switching performance.

According to a second aspect of the present invention, in the signal changeover switch according to the first aspect, the impedance conversion circuit includes an inductance of a bonding wire or a lead of a semiconductor integrated circuit on which the switch circuit is formed, and the semiconductor device. It is characterized by using the stray capacitance of an integrated circuit.

In the embodiment of the present invention, since the inductance and the stray capacitance of the bonding wires or leads of the semiconductor integrated circuit on which the switch circuit is formed are used for the impedance conversion circuit, the signal changeover switch is used. Can be reduced in the number of components. Further, the chip area of the semiconductor integrated circuit including the switch circuit and the impedance conversion circuit can be reduced.

Therefore, the size of the signal changeover switch can be reduced and the manufacturing cost can be reduced.

According to a third aspect of the present invention, in the signal changeover switch according to the first or second aspect, the impedance conversion circuit includes an inductance, a capacitance, and a transmission line formed in a dielectric multilayer substrate. It is characterized by having.

As described above, by laminating the inductance, the capacitance and the bonding wires constituting the impedance conversion circuit in the dielectric multilayer substrate, the impedance conversion circuit can be formed in a small area.
The size of the signal changeover switch can be reduced.

According to the third aspect of the present invention, the Q value of the impedance conversion circuit can be reduced, and wide-band impedance conversion can be realized. Therefore, the performance of the signal changeover switch can be improved over a wide band.

[0032] The embodiment described in claim 4 corresponds to claims 1 to
3. The signal changeover switch according to claim 3, wherein the impedance conversion circuit includes a DC cut capacitance for operating a single positive power supply and a high-frequency choke inductance.

According to this embodiment, since the high-frequency choke inductance and the DC cut capacitance for operating a single positive power supply are used as a part of the impedance conversion circuit, the number of elements of the signal switch can be reduced. When configured as a semiconductor integrated circuit, the chip area can be reduced. Therefore, the manufacturing cost can be reduced.

[0034] The embodiment described in claim 5 corresponds to claims 1 to 5.
4. The signal changeover switch according to 4, wherein the impedance as viewed from each of the impedance conversion circuits from the input / output terminal is substantially equal to the optimum impedance required by each of the external circuits.

According to the fifth aspect of the present invention, since the impedance conversion circuit has a matching function by an optimum impedance with an external circuit connected to the input / output terminal, the impedance conversion circuit can connect the input / output terminal to the external circuit. There is no need to provide a matching circuit between them.

Since no matching circuit is required between each input / output terminal and the external circuit, it is possible to reduce the conversion loss in the whole communication system or the like with the performance of the signal changeover switch improved. Furthermore, reducing the number of elements,
In a semiconductor integrated circuit, the chip area can be reduced, so that the manufacturing cost of the signal changeover switch can be reduced.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 4 is a circuit diagram showing a signal changeover switch 11 according to an embodiment of the present invention. The signal changeover switch 11 includes a switch circuit 12 using a semiconductor element such as GaAs MESFET as the switching elements Q _{1 to} Q ₄ , an ANT terminal as an input / output terminal,
RX terminal and TX terminal, impedance conversion circuit M1
To M3. Here, switch circuit 1
2 is a signal changeover switch (SP
DT switch), the same components are denoted by the same reference numerals and description thereof will be omitted. The impedance conversion circuit M1 is connected between the ANT terminal and the switch circuit 12, so that the impedance Z _SW from the switch circuit 12 to the impedance conversion circuit M1 is smaller than the impedance Z ₀ from the ANT terminal to the external circuit. . Similarly, the impedance conversion circuit M2 has R
The impedance conversion circuit M3 is connected between the X terminal and the switch circuit 12, and the impedance conversion circuit M3 is connected between the TX terminal and the switch circuit 12.
RX terminal or TX impedance ZS _W viewed the terminal is set to be smaller than the impedance Z ₀ of viewing the external circuit from the RX terminal or TX terminal from ～M3.

In the signal changeover switch 11, impedance conversion circuits M1 to M3 are provided between the switch circuit 12 and the ANT terminal, RX terminal, and TX terminal, which are input / output terminals, respectively. Since the impedance Z _SW viewed from the impedance conversion circuits M1 to M3 is set to be smaller than the impedance Z ₀ viewed from the ANT terminal, the RX terminal, and the TX terminal to the external circuit, the voltage wave of the signal power propagating inside the switch circuit 12 is reduced. Can be reduced. Therefore, the amplitude of the voltage wave superimposed on the gate-source voltage around the control voltage of the switching elements Q _{1 to} Q ₄ becomes small, and even when a high-power signal is input, each switching element Q ₁ ~Q it is possible to maintain stably the switching state of _4, it is possible to improve the maximum transmittable power, switching performance at low voltage operation improves the (insertion loss, isolation, distortion characteristics, etc.). In addition, the gate and at the time of OFF of the switching element Q ₁ ~Q ₄
Semiconductor element source voltage reaches the gate reverse breakdown voltage V _B can be prevented from breaking. Further, it is possible to prevent the gate-source voltage from reaching the rising voltage _VTH of the gate forward current when the semiconductor element is turned on, causing a large gate current to flow and deteriorating the switching performance.

In the present invention, generally speaking, the impedance seen from the switch circuit 12 to the external circuit is reduced by the impedance conversion circuits M1 to M3, and the voltage amplitude of the signal flowing through the switch circuit 12 is reduced. is there. That is, when the impedance viewed an external circuit from the switch circuit 12 and Z _SW, if the signal power P is sent, the maximum amplitude V _SW voltage wave transmitted to the switching circuit 12 is V _SW = (2ZS _W P) ^Since it is represented by ^1/2 , the signal voltage V _SW flowing through the switch circuit 12 can be reduced by reducing the impedance Z _SW of the switch circuit 12. Therefore, the switching element Q ₁
It is possible to prevent the deterioration of the switching performance at low voltage operation to Q _4. In the present embodiment, the GaAs MESFET is used as an example of the switching elements Q _{1 to} Q _4. However, even if another semiconductor element, for example, a PIN diode or the like is used, a signal of a large voltage is applied to a switch circuit using a low-voltage power supply. It is possible to prevent occurrence of switching and to prevent deterioration of switching performance (the same applies to the following embodiments).

(Second Embodiment) FIG. 5 is a circuit diagram showing a signal changeover switch 13 according to another embodiment of the present invention. The impedance conversion circuit M1 is composed of an L-type connected inductance L _ANT and capacitance C _ANT.
When the signal frequency is f, the impedance due to the inductance _LANT is j (2π
f) L _ANT = j25Ω, impedance due capacitance C _ANT is -j / (2πfC _ANT) = - it has become J50omu. Therefore, when the impedance seen from the ANT terminal to the external circuit is Z ₀ = 50Ω, the impedance seen from the switch circuit 12 to the impedance conversion circuit M1 is Z _SW = 25Ω. Similarly, the impedance conversion circuit M2, M3, the inductance L _RX which are respectively L-type connection, L _TX and the capacitance CR _X, a L-type non-loss circuit consisting of a C _TX, inductance L _RX, impedance due L _TX is j (2πf) L _RX = j25Ω, j (2π
f) L _TX = j25Ω, impedance by capacitances C _RX and C _TX is −j / (2πfC _RX ) = − j50Ω,
−j / (2πfC _TX ) = − j50Ω. Therefore, when the impedance of the external circuit viewed from the RX terminal or the TX terminal is Z ₀ = 50Ω, the switching circuit 12
The impedance seen at the X terminal or TX terminal is also Z _SW = 25
Ω. Note that the inductances L _ANT , L _RX , L _TX ,
The element constants of the capacitances C _ANT , C _RX , and C _TX are determined by the frequency f of the signal flowing through the circuit, and at 1.9 GHz, L _ANT = L _RX = L _TX = 2.094 nH, C _ANT
= C _RX = C _TX = 1.675 pF.

FIGS. 6 and 7 show the input terminal (ie, TX terminal or ANT terminal), the inside of the switch circuit 12, and the output terminal (ie, ANT terminal) when a signal power of 360 mW is input to the signal changeover switch 13. FIG. 3 is a diagram showing a voltage waveform and a current waveform at the (RX terminal). However, for the sake of simplicity, the calculation is performed on the assumption that the resistance loss inside the switch circuit 12 is zero. Since the ANT terminal, the RX terminal, and the TX terminal, which are the input / output terminals, are based on Z ₀ = 50Ω, the maximum amplitude of the voltage wave is 6 V [= (2P
Z ₀ ) ^1/2 ], and the maximum amplitude of the current wave is 120 mA [= (2P
/ Z ₀₎ but it becomes ^1/2], ZS _W = 2 by the impedance conversion circuit M1~M3 the inside of the switch circuit 12
Since it is a 5Ω system, the maximum amplitude of the voltage wave is 4.24.
V [= (2PZ _SW ) ^1/2 ], the maximum amplitude of the current wave is 170
mA [= (2P / Z _SW ) ^1/2 ].

The ANT terminal which is an input / output terminal,
When a signal power of 360 mW is input from the RX terminal and the TX terminal, the maximum amplitude of the voltage wave propagating through the switch circuit 12 should reach 6 V due to the impedance Z ₀ = 50Ω, but the impedance Z is determined by the impedance conversion circuits M1 to M3. _SW is 25Ω (1/0 of impedance Z ₀ )
(2 times), the maximum amplitude of the voltage wave propagating through the switch circuit 12 is reduced to 4.24 V (1 / √2 times). Instead, the maximum amplitude of the current wave is 120 m at Z ₀ = 50Ω.
A, but increased by a factor of 2 to 170 mA at Z _SW = 25Ω.

As described above, the impedance conversion circuits M1 to M3 are provided between the input / output terminals ANT terminal, RX terminal, TX terminal and the switch circuit 12, and the switch circuit 1
2 so that the impedance Z _SW as viewed from the impedance conversion circuits M1 to M3 is smaller than the impedance Z ₀ as viewed from the input / output terminals ANT, RX and TX terminals to the external circuit.
Is designed, the amplitude of the voltage wave of the signal power propagating inside the switch circuit 12 can be reduced.

Accordingly, the amplitude of the voltage wave superimposed on the gate-source voltage around the control voltage of the switching elements Q _{1 to} Q ₄ becomes small, and even when a high power signal is input, each of the switching elements The switching states of the elements Q _{1 to} Q ₄ can be kept stable, and the maximum transmittable power and the switching performance (insertion loss, isolation, distortion characteristics, etc.) in low-voltage operation can be improved.

Further, as shown in FIG. 2, when the OFF during the gate-source voltage of the switching element Q ₁ to Q ₄ reaches the gate reverse breakdown voltage V _B of the switching element Q ₁ to Q ₄ switching elements Although disruption of Q ₁ to Q ₄ may occur, according to the present invention, it is possible also to alleviate this breakdown voltage limit.

Further, the switching elements Q _{1 to} Q ₄ are
When the voltage between the gate and the source reaches the rising voltage _VTH of the gate forward current at the time of N, a large gate current flows and the switching performance is deteriorated. However, according to the present invention, this effect can be reduced.

These effects are attributable to the lowering of the impedance inside the switch circuit 12 by the impedance conversion circuits M1 to M3 and the reduction of the voltage amplitude. In this embodiment, the switching element is made of GaAs MESF as an example.
Although the ET is used, it is possible to relax the voltage limitation such as the withstand voltage in other switching semiconductor elements, for example, a PIN diode.

(Third Embodiment) FIG. 8 is a plan view showing a signal changeover switch 14 according to another embodiment of the present invention. In the signal changeover switch 14, the switch circuit 12 is formed on an IC (semiconductor integrated circuit) chip 15. Reference numerals 16, 17, and 18 denote ANT-side terminal electrodes, RX-side terminal electrodes, and TX-side terminal electrodes of the switch circuit 12 formed on the IC chip 15, respectively. The IC chip 15 on which the switch circuit 12 is formed is die-bonded on the die pad 19. Three ground terminals 20 extend from the die pad 19. Also,
Mold package 21 encapsulating IC chip 15
, An ANT lead 22 serving as an ANT terminal, an RX lead 23 serving as an RX terminal, and a TX lead 2 serving as a TX terminal.
Each end of 4 is embedded. The ANT lead 22 and the ANT terminal electrode 16 of the switch circuit 12 are connected by a bonding wire 25, the RX lead 23 and the RX terminal electrode 17 of the switch circuit 12 are connected by a bonding wire 26, and the TX lead 24 The TX side terminal electrode 18 of the switch circuit 12 is connected by a bonding wire 27. Also, 28, 29, 30
Are the ANT side terminal electrode 16 and the RX side terminal electrode 1 respectively.
7, a ground electrode provided in the vicinity of the TX-side terminal electrode 18, and a die pad 19 via a via hole 31.
It is conducting. The ANT terminal electrode 16a and the ground electrode 28 of the switch circuit 12 are connected by an MIM capacitor 32 formed on the IC chip 15, and the RX terminal electrode 17a and the ground electrode 29
The TX terminal electrode 18a and the ground electrode 30 are connected by an MIM capacitor 34.

FIG. 9 is an equivalent circuit diagram of the signal changeover switch 14. In the signal changeover switch 14, the ANT terminal, the RX terminal, the TX terminal and the switch circuit 1
2, impedance conversion circuits M1 to M1
M3 is an L-shaped circuit composed of inductances L _L1 , L _L2 , L _L3 and capacitances C _S1 , C _S2 , C _S3 , inductances L _W1 , L _W2, and capacitances C _M1 , C _M2 , C
_{It has} a two-stage configuration of an L-type circuit composed of _M3 .

In the impedance conversion circuit M1,
The tip of the ANT lead 22 is an ANT terminal, the inductance L _L1 is constituted by the inductance of the ANT lead 22, and the capacitance C _S1 is the ANT lead 2
The inductance L _W1 and L _W2 are formed by the inductance of the bonding wire 25, and the large capacitance C _M1 is formed by the MIM capacitance 32.

Similarly, in the impedance conversion circuit M2, the tip of the RX lead 23 is an RX terminal, the inductance L _L2 is constituted by the inductance of the RX lead 23, and the capacitance C _S2 is equal to the RX lead 23 and the ground terminal 20. , The inductances L _W1 and L _W2 are formed by the inductance of the bonding wire 26, and the large capacitance C _M2 is formed by the MIM capacitance 33.

Similarly, in the impedance conversion circuit M3, the tip of the TX lead 24 is a TX terminal, the inductance L _L3 is constituted by the inductance of the TX lead 24, and the capacitance C _S3 is the connection between the TX lead 24 and the ground terminal 20. The inductances L _W1 and L _W2 are formed by the inductance of the bonding wire 27, and the large capacitance C _M3 is formed by the MIM capacitance 34.

According to the present embodiment, the ANT lead 22, the RX lead 23, and the TX lead 2 which pose a problem when the signal changeover switch 14 is accommodated in the mold package 21.
4, the inductances L _L1 , L _L2 , L _L3 , L _W1 , L _W2 , and ANT lead 2 of the bonding wires 25, 26, 27
2, RX lead 23, TX lead 24 and ground terminal 2
The stray capacitances C _S1 , C _S2 , and C _S3 between 0 can be positively used as a part of the impedance conversion circuits M1 to M3, and the chip area of the IC chip 15 can be reduced, and signal switching can be performed. With the performance of the switch 14 improved, the area of the IC chip 15 can be reduced, and the manufacturing cost can be reduced.

(Fourth Embodiment) FIG. 10 is a perspective view showing a signal changeover switch 35 according to still another embodiment of the present invention, and FIG. 11 is an equivalent circuit diagram thereof. In the signal changeover switch 35, the impedance conversion circuit M
The IC chip 15 on which the switch circuit 12 is formed is mounted on the upper surface of the dielectric multilayer substrate 36 in which 1 to M3 are configured, and the IC chip 15 and the dielectric multilayer substrate 36 are connected by bonding wires 37.

As shown in FIG. 11, the impedance conversion circuits M1 to M3 include inductances L _A1 , L _A2 , L _A3 ; L _B1 , L A formed in multiple stages inside the dielectric multilayer substrate 36.
_B2 , L _B3 ; L _C1 , L _C2 , L _C3 and capacitances C _A1 , C
Is constituted by _{MS 3; A2, C A3;} C B1, C B2, C B3; C C1, C C2, C C3 and the transmission line MS _1; MS _2.

In the impedance conversion circuit M1,
An inductance L _A1 , a capacitance C _A1 , a transmission line MS ₁ , and an inductance L _A3 are connected in series between the ANT terminal and the switch circuit 12, and a connection point between the inductance L _A1 and the capacitance C _A1 is connected to the G via the inductance L _A2.
ND, the capacitance C _A1 and the transmission line MS1
Is connected to GND via a capacitance C _A2, and a connection point between the transmission line MS ₁ and the inductance L _A3 is connected to GND via a capacitance C _A3 .

Similarly, the impedance conversion circuit M2 (M
In 3), the inductance L _B1 (L _C1 ), the capacitance C _B1 (C _C1 ), the transmission line MS ₂ (MS ₃ ), and the inductance L _B3 (L _C3 ) are connected in series between the RX terminal (TX terminal) and the switch circuit 12. ) Is connected and the inductance L _B1
A connection point between (L _C1 ) and the capacitance C _B1 (C _C1 ) is connected to GND via an inductance L _B2 (L _C2 ), and a connection point between the capacitance C _B1 (CC ₁ ) and the transmission line MS ₂ (MS ₃ ). Is connected to GND via a capacitance C _B2 (C _C2 ), and a transmission line MS ₂ (MS ₃ ) and an inductance L
A connection point of _B3 (L _C3 ) is connected to GND via a capacitance C _B3 (C _C3 ). Note that the inductance of the bonding wire 37 is different from the impedance conversion circuit M1.
To M3, and the bonding wire 37 is a part of the impedance conversion circuits M1 to M3.

As described above, the impedance conversion circuit M1
To M3 are formed on the dielectric multilayer substrate 36, so that the impedance conversion circuits M1 to M3 can be mounted in a small mounting area.
M3 is the inductance L _{A1 to} L _C3 , the capacitance C _A1
To C _C3 , the transmission lines MS _{1 to} MS _3, and the bonding wires 37.

Therefore, the impedance conversion circuits M1 to M
3 can be reduced, and wide-band impedance conversion can be realized. Therefore, the performance of the switch circuit 12 can be improved over a wide band. The impedance conversion circuits M1 to M3 are connected to the dielectric multilayer substrate 36.
Therefore, the mounting area can be reduced, and the size of the signal changeover switch 35 can be reduced.

(Fifth Embodiment) FIG. 12 is a circuit diagram showing a signal changeover switch 38 according to still another embodiment of the present invention. The signal changeover switch 38 has a DC cut capacitance C _DC and a high frequency choke inductance L _RF added to realize a single positive power supply operation. The DC cut capacitance C _DC and the high frequency choke inductance L _RF Are part of the impedance conversion circuits M1 to M3.

That is, the impedance conversion circuit M1
Is a DC cut capacitance C _DC inserted between the ANT terminal and the switch circuit 12, and an inductance L _G inserted in series between a connection point between the DC cut capacitance C _DC and the ANT terminal and GND. , And a high-frequency choke inductance L _RF connected to a connection point between the DC cut capacitance C _DC and the switch circuit 12 and applied with a constant voltage V _DD .

Further, the impedance conversion circuit M 2
And the capacitance C _DC DC blocking inserted between the X terminal and the switch circuit 12, and the inductance L _G which are inserted in series between the connection point and the GND between the DC cut capacitance C _DC and RX terminals, switching Element Q ₂
DC cut capacitance C _DC inserted between the DC cut capacitance C _DC and the switching element Q ₂ , and a high frequency choke inductance L _RF to which a constant voltage V _DD is applied and which is connected to the connection point between the DC cut capacitance C _DC and the switching element Q _2. It is composed of

Similarly, the impedance conversion circuit M3
And the capacitance C _DC DC blocking inserted between the TX terminal and the switch circuit 12, and the inductance L _G which is inserted between the connection point and the GND between the DC cut capacitance C _DC and TX terminals, the switching element Q ₄ and G
DC cut capacitance C _DC inserted between ND
When it is configured from this DC cut capacitance C _DC and is connected to the connection point of the switching element Q ₄ high-frequency choke inductance L _RF applied a constant voltage V _DD (shared with the impedance conversion circuit M2).

[0064] The signal switching switch 38, so use as part of the impedance conversion circuit M1~M3 inductance for high-frequency choke for a single positive power supply operation L _RF and DC cut capacitance C _DC as described above In addition, the number of elements of the signal changeover switch 38 can be reduced, and the chip area can be reduced when configured as a semiconductor integrated circuit.

(Sixth Embodiment) FIG. 13 is a diagram showing a signal changeover switch 39 according to still another embodiment of the present invention together with an external circuit. A transmission / reception antenna 40 is connected to the ANT terminal, a reception low noise amplifier (LNA) 41 is connected to the RX terminal, and a transmission power amplifier (PA) 42 is connected to the TX terminal.

In this signal changeover switch 39,
From the switch circuit 12 to the impedance conversion circuits M1 to M
The impedance Z _SW viewing the 3, smaller than the ANT terminal, transmitting and receiving antenna 40 from the RX terminal and the TX terminal, the receiving low noise amplifier 41, the impedance Z ₀ viewed an external circuit such as a transmission power amplifier 42, further, the ANT terminal ,
From the RX terminal and the TX terminal to each impedance conversion circuit M
The transmission / reception antenna 40 which detects the impedances from 1 to M3,
Receiving low noise amplifier 41, the optimum impedance (Rated impedance) of the external circuit is required, such as transmission power amplifier 42 Z _ANT, Z _LNA, such as the Z _PA, each impedance conversion circuit M1~M3 is designed. As a result, the ANT terminal, RX terminal, TX
It has a matching function with the optimum impedance to the external circuit connected to the terminal.

Here, the optimum impedance means that in the transmitting / receiving antenna 40, all the transmitting power input from the transmitting circuit to the transmitting / receiving antenna 40 is radiated into the air, and conversely, all the receiving power incident from the air is output to the receiving circuit. Impedance Z _ANT . In the transmission power amplifier 42, the impedance Z _PA at which the maximum output power is obtained is obtained.
It is. In the receiving low-noise amplifier 41, the impedance Z _LNA at which the minimum noise figure is obtained.

If the signal changeover switch 39 does not have a matching function using the optimum impedance, the transmission / reception antenna 40, the transmission power amplifier 42, and the reception low noise amplifier 4
When an external circuit such as 1 is connected to the ANT terminal, TX terminal, and RX terminal, A
After converting the characteristic impedance (for example, 50Ω) of the NT terminal, the TX terminal, and the RX terminal with the external circuit to the optimal impedance required by the external circuit, the transmitting / receiving antenna 40 is connected to the ANT terminal, the TX terminal, and the RX terminal via the matching circuit. Power amplifier 42 for transmission, low noise amplifier 41 for reception
It is necessary to connect an external circuit such as.

On the other hand, in the signal changeover switch 39 according to the present embodiment, the impedance conversion circuits M1 to M3
The ANT terminal, TX terminal and RX terminal have a matching function with the optimal impedance with the external circuit connected to the ANT terminal, TX terminal and RX terminal. Therefore, a matching circuit between the ANT terminal, RX terminal and TX terminal and the external circuit becomes unnecessary. In addition, the configuration when connecting to an external circuit can be simplified.

Further, since a matching circuit connected between the ANT terminal, the RX terminal, the TX terminal and the external circuit becomes unnecessary, the signal switching switch 39 and the communication The conversion loss in the system can be reduced, the number of elements can be further reduced, and when a semiconductor integrated circuit is used, the chip area can be reduced, and the manufacturing cost of the signal switch 39 can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional signal changeover switch.

FIG. 2 is a diagram illustrating characteristics of a switching element and a signal voltage superimposed on a control voltage applied to a gate of the switching element.

FIG. 3 is a circuit diagram showing another conventional example, which is a signal changeover switch in which switching elements are connected in multiple stages.

FIG. 4 is a circuit diagram showing a signal changeover switch according to an embodiment of the present invention.

FIG. 5 is a circuit diagram showing a signal changeover switch according to another embodiment of the present invention.

FIG. 6 is a diagram showing an input terminal, an output terminal, and a voltage waveform inside the switch circuit when a signal power is input to the signal changeover switch according to the first embodiment.

FIG. 7 is a diagram showing an input terminal, an output terminal, and a current waveform in a switch circuit when signal power is input to the signal changeover switch of the above.

FIG. 8 is a plan view showing a signal changeover switch according to still another embodiment of the present invention.

FIG. 9 is a circuit diagram showing an equivalent circuit of the above signal changeover switch.

FIG. 10 is an external perspective view showing a signal changeover switch according to still another embodiment of the present invention.

FIG. 11 is a circuit diagram showing an equivalent circuit of the above signal changeover switch.

FIG. 12 is a circuit diagram showing a signal changeover switch according to still another embodiment of the present invention.

FIG. 13 is a circuit block diagram showing a signal changeover switch according to still another embodiment of the present invention.

[Explanation of symbols]

Q _{1 to} Q ₄ Switching elements M ₁ to M ₃ Impedance conversion circuits L _ANT , L _{L1 to} L _L3 , L _W1 , L _W2 , L _{A1 to} L _A3 , L _B1 to
L _B3 , L _{C1 to} L _C3 inductance C _ANT , C _{S1 to} C _S3 , C _{M1 to} C _M3 , C _{A1 to} C _A3 , C _B1 to
C _B3 , C _{C1 to} C _C3 Capacitance MS _{1 to} MS ₃ Transmission Line L _RF High Frequency Choke Inductance C _DC DC Cut Capacitance ANT ANT Terminal RX RX Terminal TX TX Terminal GND Ground 12 Switch Circuit 15 IC Chip 36 Dielectric Multilayer Substrate

Claims (5)

[Claims] A switch circuit in which a semiconductor element is used as a switching element; and a plurality of input / output terminals. The input / output terminals are connected to each other by the switch circuit.
In a signal changeover switch for disconnecting, an impedance conversion circuit is provided between the input / output terminal and the switch circuit, and the impedance of the impedance conversion circuit viewed from the switch circuit is smaller than the impedance of the external circuit viewed from the input / output terminal. A signal changeover switch characterized in that: 2. The method according to claim 1, wherein the impedance conversion circuit uses an inductance of a bonding wire or a lead of the semiconductor integrated circuit on which the switch circuit is formed, and a stray capacitance of the semiconductor integrated circuit. The signal changeover switch according to claim 1. 3. The impedance conversion circuit according to claim 1, wherein the impedance conversion circuit includes an inductance, a capacitance, and a transmission line formed in a dielectric multilayer substrate.
The signal changeover switch according to claim 1. 4. The signal changeover switch according to claim 1, wherein the impedance conversion circuit includes a DC cut capacitance for operating a single positive power supply and a high frequency choke inductance. 5. The signal changeover switch according to claim 1, wherein the impedance as viewed from each of said impedance conversion circuits from said input / output terminal is substantially equal to the optimum impedance required by each of said external circuits. .