KR20040076681A - Dual band front end module - Google Patents

Abstract

PURPOSE: A dual band front end module is provided to attain a small size and light weight by reducing the number of diodes and capacitors and extend call standby time by reducing battery consumption. CONSTITUTION: A PA(Power Amplifier) module(22) amplifies a signal transmitted from GSM and DCS sending terminals(Tx). The first and second phase shifters(24a,24b) change transmission and reception paths of the GSM signal. The third and fourth phase shifters(25a,25b) changes transmission and reception paths of the DCS signal. The first LPF(Low Pass Filter)(23a) cancels RF noise of a signal which has passed the first phase shifter(24a). The second LPF(23b) cancels RF noise of a signal which has passed the third phase shifter(25a). An antenna(27) transmits signals received from the DCS and GSM sending terminals to DCS and GSM receiving terminals. A diplexer(26) separates a signal received from the antenna(27) into an RF band(DCS) and a low frequency band(GSM) and determines which side it should be connected. The first SAW BPF(Band Pass Filter)(21a) passes only a signal of a certain range of frequency band desired by the GSM receiving end(Rx) and removes a signal that is not included in the range. The second SAW BPF(21b) passes only a signal of certain range of frequency band and removes a signal that is not included in the range.

Description

Dual Band Front End Modules {DUAL BAND FRONT END MODULE}

The present invention relates to a dual band front end module, and more particularly, to a dual band front end module capable of miniaturization and weight reduction by reducing the number of diodes and capacitors, and reducing the battery consumption to increase call waiting time. will be.

1 is a view showing the configuration of a front end of a conventional dual band terminal.

As shown in FIG. 1, the conventional dual band front end unit 10 includes a PA module 12 for amplifying a signal transmitted from a GSM and a DCS transmitter Tx, and a GSM transmitter Tx. A first low pass filter (13a) for removing high frequency noise of a signal transmitted through the PA module 12 and a signal transmitted from the DCS transmitter Tx and passed through the PA module 12 A second LPF 13b for removing high frequency noise, a first switch 15a for changing a transmission path and a reception path of the GSM signal, and a second switch 15b for changing a transmission path and a reception path of the DCS signal ), An antenna 17 for transmitting the signals transmitted from the DCS transmitter and the GSM transmitter to the DCS receiver and the GSM receiver, and a high frequency band corresponding to the frequency band of each system among the signals received from the antenna 17. DCS) and low frequency band (GSM) A diplexer 16 which determines which side to connect to, a first phase shifter 14a (P.S2) which is separated by the diplexer 16 into a desired GSM low frequency band, and the first phase shifter A first SAW band pass filter (11a) for passing a signal of a desired frequency band (925 to 960 MHz) in a GSM receiver (Rx) and removing a signal outside this range, and the diple The second phase shifter 14b (P.S4) separated by the lexer 16 into a desired DCS high frequency band, and a predetermined range of frequency bands desired by the DCS receiver Rx for the signal passing through the second phase shifter ( And a second SAW BPF 11b for passing only signals of 1805-1880 MHz and removing signals outside this range.

2 is a block diagram showing the configuration of a conventional PA module 12. As shown in FIG.

As shown in Fig. 2, the conventional power amplifier (PA) module 12 includes an amplifier circuit PA 12a, 12b having a GaAs transistor element and an input match connected to an input side of the amplifier circuits 12a, 12b. Circuits (Input Matching: 18a, 18b) and output matching circuits (Output Matching: 19a, 19b) connected to the output side of the amplifier circuits 12a, 12b.

Here, the output impedance of the PA itself generally has a very low impedance.

In addition, in the case of GSM using TDMA, since the PA module is not always on, the output impedance of the operating and stopping states has a different value. The state has a very low impedance in the receive frequency band.

3 is a circuit diagram including a conventional dual band antenna switch and SAW BPF.

Referring to the configuration of FIG. 3 compared to the configuration of FIG. 1, the illustration of the high frequency amplifier (PA module) 12 is omitted, and the diodes D1 and D2 serve as the first switch 14, and the diodes D3, D4 serves as the second switch 15.

Referring to FIG. 3, the operation of the conventional dual band front end module circuit will be described.

In transmission mode, that is, in GSM transmission mode, diodes D1 and D2 are on, and in DCS transmission mode, diodes D3 and D4 are on.

When diodes D2 and D4 are turned on, the impedances of p2 and p4 are low (short circuit).

At this time, the impedance seen toward the receiving end from the connection points p1 and p3 becomes very large because PS2 and PS4 have a length of λ / 4 and the inductance of the diode (not shown) and the capacitors Ch and Ch 'grounded to ground resonate. ).

As a result, the transmission signal in the transmission circuit is transmitted to the antenna without leaking to the reception circuit.

However, since the diodes D1 and D2 connected in series between the transmission circuits in the transmission mode act as a resistance in the on state, there is a problem of increasing the loss of the transmission signal.

In addition, since the bias current must flow through the diode at the time of transmission, battery consumption is generated, which reduces the talk time of the mobile phone, which makes it difficult to reduce power consumption.

In addition, due to the increase in the number of diodes, the stack module has a problem that it is difficult to reduce the size and weight of a wireless communication device having a dual band or more.

Disclosure of Invention The present invention has been made to solve the above problems, and aims to provide a dual band front end module that can reduce the number of diodes, reduce weight, and reduce battery consumption and increase call waiting time. It is done.

1 is a view showing the configuration of a front end of a conventional dual band terminal.

2 is a block diagram showing the configuration of a conventional PA module.

3 is a circuit diagram including a conventional dual band antenna switch and SAW BPF.

4 illustrates a dual band front end module according to a first embodiment of the present invention including a PA module.

5 is a circuit diagram of a dual band front end module according to a first embodiment of the present invention.

6 is a circuit diagram of a dual band front end module according to a second embodiment of the present invention.

7 is a circuit diagram of a dual band front end module according to a third embodiment of the present invention.

8 is a diagram illustrating a connection terminal of a dual band front end module chip according to the present invention.

9 is a cross-sectional view illustrating a chip package of a dual band front end module according to the present invention.

<Description of Major Symbols in Drawing>

21a, 21b: SAW BPF 22: PA Module

23a, 23b: LPF 24a, 24b, 25a, 25b: phase shifter

26: diplexer 27: antenna

In order to achieve the above object, the dual-band front end module according to the present invention, the PA module for amplifying a signal transmitted from the first frequency band and the second frequency band transmitting end, the transmission path and the reception path of the first frequency band signal A first and second phase shifters for changing a signal, a third and fourth phase shifters for changing a transmission path and a reception path of the second frequency band signal, and a high frequency noise of the signal passing through the first phase shifter A first LPF, a second LPF for removing high-frequency noise of the signal passing through the third phase shifter, and a signal transmitted from the second frequency band transmitting end and the first frequency band transmitting end to the second frequency band receiving end and the first frequency band. An antenna for transmitting the signal to a frequency band receiver and a frequency band of each system among the signals transmitted from the antenna A diplexer for determining which of the second frequency band and the first frequency band to connect to, and at the first frequency band receiving end Rx in a frequency band separated by the diplexer into the first frequency band. A first BPF that passes only signals in a desired range of frequencies and a signal in a desired range of frequencies in the second frequency band receiver Rx in a frequency band separated by the diplexer into the second frequency band. And a second BPF.

The first and second frequency bands are GSM and DCS frequency bands, and the first and second BPFs are SAW BPFs.

In addition, the first and third capacitors to prevent the DC signal of the power supply terminals Vc1 and Vc2 for supplying power to the diode switch to the antenna, and the DC signal of the power supply terminals Vc1 and Vc2 is introduced into the transmission circuit. In addition to preventing, the PA module includes a second and a fourth capacitor to prevent the DC power signal from flowing into the ASM circuit.

In addition, an inductance connected in series with the phase shifter is included to resonate with the second capacitor or the fourth capacitor.

In addition, the first capacitor and the third capacitor is removed, it characterized in that it comprises a capacitor connected in series between the antenna and the diplexer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 illustrates a dual band front end module 20 according to a first embodiment of the present invention including a PA module.

As shown in FIG. 4, the dual band front end module 20 according to the present invention includes a PA module (Power Amplifier Module) 22 for amplifying signals transmitted from GSM and DCS transmitters (Tx), and the GSM signals. First and second phase shifters 24a and 24b for changing a transmission path and a reception path of the first and second phase shifters 25a and 25b for changing a transmission path and a reception path of the DCS signal, and A first low pass filter (LPA) 23a for removing high frequency noise of the signal passing through the first phase shifter 24a and a high frequency noise of the signal passing through the third phase shifter 25a are removed. A second LPF (23b), an antenna (27) for transmitting the signals transmitted from the DCS transmitter and the GSM transmitter to the DCS receiver and the GSM receiver, and a signal transmitted from the antenna (27) In response to the frequency bands in the high frequency band (DCS) and low frequency band (GSM) Signal of a predetermined range of bands (925-960 MHz) desired by the GSM receiver Rx in a frequency band separated by a low frequency band by the diplexer 26 and a diplexer 26 for determining which side to connect to. A first SAW band pass filter (21a) for passing only a signal and removing a signal outside this range, and a desired range of a desired range at the DCS receiver Rx in a frequency band separated by a high frequency band by the diplexer 26; And a second SAW BPF 21b for passing only signals in the frequency band 1805-1880 MHz and removing signals outside this range.

Here, the high frequency amplifier 22 has an impedance characteristic that is 50 ohms in the frequency band of the transmission signal during operation, but is almost short-circuited in the frequency band of the reception signal when stopped.

5 is a circuit diagram of a dual band front end module 20 according to a first embodiment of the present invention.

Referring to FIG. 5, according to the first embodiment of the present invention, in the antenna 27, the receiver RF SAW filters 21a and 21b, and the high frequency amplifier PA 22, etc. The phase shifters P. S1 and P. S3 perform the role instead of the diode switches D1 and D3 which perform the transmission / reception path separation of the GSM signal and the transmission / reception path separation of the DCS signal. In other words, by reducing the number of diodes can be miniaturized and lightweight, and the battery standby time can be increased by reducing the battery consumption.

Hereinafter, a circuit operation of the dual band front end module according to the first embodiment of the present invention will be described with reference to FIG. 5.

In the first embodiment according to the present invention, the diode D2 is turned on in the GSM transmission mode. Therefore, the second phase shifter P. S2: 24b is connected to the ground through the capacitor Ch and has a low impedance. However, the impedance seen toward the receiving end from the branching points of P. S1 24a and P. S2 24b is seen to have a large impedance through P.S2 24b.

At this time, the inductance (not shown) of D2 in the On state and the capacitor Ch resonate in series, whereby the impedance of the receiving circuit becomes very large. Therefore, the transmission signal amplified by the PA module 22 is transmitted to the antenna 27 through the P. S1 24a without leaking to the receiving circuit.

In GSM receive mode, diode D2 is off. At this time, since the PA module 22 is in a non-operating state, the output impedance has a very low impedance.

Therefore, the impedance viewed toward the transmitting circuit from the branching points of P. S1 24a and P. S2 24b has a large impedance through the phase shift circuit P. S1 24a.

Therefore, the received signal received at the antenna 27 is transmitted to the receiving end without leakage to the transmitting end circuit.

In the operation of the DCS transmission mode and the reception mode, the roles of P.S1 (24a) and P.S2 (24b) are changed to P.S3 (25a) and P.S4 (25b), respectively. As it is described as follows, it is omitted.

Here, PS 1 24a has a length of λ / 4 of the wavelength λ at the center frequency of the GSM-Rx band, and PS 2 24b has a length of λ / 4 of the wavelength λ at the center frequency of the GSM-Tx band. Have

In addition, PS 3 (25a) has a length of λ / 4 of the wavelength λ at the center frequency of the DCS-Rx band, and PS 4 (25b) has a length of λ / 4 of the wavelength λ at the center frequency of the DCS-Tx band. Have

In addition, the first capacitor Cd1 and the third capacitor Cd3 prevent the DC signals of the power terminals Vc1 and Vc2 that apply power to the diode switch from flowing into the antenna 27.

In addition, the second capacitor Cd2 and the fourth capacitor Cd4 not only prevent the DC signals of the power terminals Vc1 and Vc2 from entering the transmission circuit, but also prevent the DC power signals of the PA module 22 from entering the ASM circuit. .

6 is a circuit diagram of a dual band front end module according to a second embodiment of the present invention.

As shown in Fig. 6, the second embodiment according to the present invention is in phase so as to resonate with Cd2 or Cd4 so that the impedance viewed from the transmitter end circuit at the branch point of P.S1 and P.S2 has a larger value in the reception mode. It differs from the first embodiment in that an inductance (Ldt) component is inserted in series with the circuits 24a and 25a.

7 is a circuit diagram of a dual band front end module according to a third embodiment of the present invention.

As shown in FIG. 7, the third embodiment of the present invention removes the block capacitors Cd3 and Cd4 which serve as DC blocking, and positions the DC blocking capacitor Cd at the terminal side of the antenna 27. The difference from the second embodiment is that circuit components (capacitors) can be reduced.

8 is a diagram illustrating a connection terminal of a dual band front end module chip according to the present invention.

As shown in Figure 8, the terminal of the dual-band FEM chip package according to the present invention, the GSM Tx, GSM Rx for transmitting and receiving the GSM signal on the center around the ground terminal on the left and right, and the ground terminal and antenna of each ceramic substrate The terminal is formed.

In addition, DCS Tx and DCS Rx for transmitting and receiving DCS signals and power terminals VC1, VC2, and ground terminals are formed below the ground terminal.

9 is a cross-sectional view illustrating a chip package of a dual band front end module according to the present invention.

As shown in FIG. 9, the chip package of the dual band front end module according to the present invention includes an LTCC incorporating phase shifters 24a, 24b, 25a, and 25b, a diplexer 26, and the like, and an LTCC substrate thereof. PA elements 22, large chip resistors and capacitors, pin diodes, and dual band SAW BPFs 21a and 21b are mounted on the top.

In addition, the passivation process may be performed according to the use environment after the mounting.

The passivation method includes a shielding method using a metal cover and an epoxy molding method.

As described above, the present invention reduces the number of diodes and the number of capacitors, thereby making it possible to reduce the size and weight of the diode and reduce the battery consumption, thereby increasing the call waiting time.

Claims (5)

A PA module for amplifying a signal transmitted from a first frequency band and a second frequency band transmitter; First and second phase shifters for changing a transmission path and a reception path of the first frequency band signal; Third and fourth phase shifters for changing a transmission path and a reception path of the second frequency band signal; A first LPF for removing high frequency noise of the signal passing through the first phase shifter; A second LPF for removing high frequency noise of the signal passing through the third phase shifter; An antenna for transmitting the signals transmitted from the second frequency band transmitting end and the first frequency band transmitting end to the second frequency band receiving end and the first frequency band receiving end; A diplexer for determining which of the signals transmitted from the antennas to be separated into the second frequency band and the first frequency band according to a frequency band of each system, and determining which one to connect to; A first BPF which passes only signals in a desired range of frequency bands desired by the first frequency band receiver Rx in a frequency band separated by the diplexer into the first frequency band; A dual band front end module comprising a second BPF for passing only signals in a desired range of frequencies in the second frequency band receiving terminal Rx in a frequency band separated by the diplexer into the second frequency band; . The method of claim 1, Wherein the first and second frequency bands are GSM and DCS frequency bands, and the first and second BPFs are SAW BPFs. The method according to claim 1 or 2, First and third capacitors for preventing DC signals from power terminals Vc1 and Vc2 for supplying power to a diode switch from being introduced into the antenna; Dual and characterized in that not only to prevent the DC signal of the power supply terminals Vc1 and Vc2 into the transmission circuit, but also to prevent the DC power signal of the PA module from flowing into the ASM circuit. Band front end module. The method of claim 3, wherein And an inductance connected in series with the phase shifter to resonate with the second capacitor or the fourth capacitor. The method of claim 3, wherein And a capacitor connected in series between the antenna and the diplexer, wherein the first capacitor and the third capacitor are removed.