Matching circuit, RF front-end power amplifier circuit and mobile communication device

Abstract

The present application relates to a matching circuit, an RF front-end power amplifier circuit, and a mobile communication device, the matching circuit being used in an RF front-end power amplifier and including: a first impedance matching box having an impedance of a first predetermined impedance at a first frequency; a first bandpass filter connected between a front end of the first impedance matching box and ground, passing the first frequency signal and suppressing at least one of a signal of a second frequency lower than the first frequency and a first harmonic signal of the first frequency signal; and a first trap connected between a back end of the first impedance matching box and ground, suppressing a second harmonic signal of the first frequency signal.

Description

[Technical field]

[0001] The present application relates to the field of mobile communications, and in particular to a matching circuit, an RF front-end power amplifier circuit, and a mobile communications device. [Background technology]

[0002] RF power amplifiers are an important part of mobile phone communication systems and are mainly used for signal amplification. With the development of mobile phone communication systems, the requirements for the radiated power of mobile phone power amplifiers are increasing. The improvement of PA radiated power leads to higher harmonics and worse spurious index, and the deterioration of harmonics and spurious seriously affects the quality of communication, so the matching circuit of the PA back-end needs to have higher suppression ability for PA harmonics and spurious.

[0003] At present, the traditional PA matching circuit lacks the ability to suppress harmonics and low-frequency spurious emissions, and the circuit is relatively complicated and difficult to implement, making it difficult to meet technical requirements. Summary of the Invention [Means for solving the problem]

[0004] In view of this, the present application provides a matching circuit for use in an RF front-end power amplifier, the matching circuit including: a first impedance matching box having an impedance of a first predetermined impedance at a first frequency; a first band-pass filter connected between a front end of the first impedance matching box and a ground, the first band-pass filter passing a first frequency signal and suppressing at least one of a signal of a second frequency lower than the first frequency and a tripled signal of the first frequency signal; a first trap connected between a back end of the first impedance matching box and a ground, suppressing a doubled signal of the first frequency signal and performing a first impedance matching in cooperation with the first impedance matching box; and a first matching unit connected to the front end of the first impedance matching box, the first band-pass filter including a first resonator and a second resonator connected in series, the first resonator including a first inductor and a first capacitor connected in parallel, the second resonator includes a second inductor and a second capacitor connected in series, the first matching unit includes a fifth inductor, a sixth inductor, a seventh inductor, and a fifth capacitor connected in series, the first matching unit further includes an eighth inductor and a sixth capacitor connected in series between a connection point between the fifth inductor and the sixth inductor and ground, a ninth inductor and a seventh capacitor connected in series between a connection point between the sixth inductor and the seventh inductor and ground, and a tenth inductor and an eighth capacitor connected in series between a connection point between the seventh inductor and the fifth capacitor and ground, wherein the first frequency is within a 1.710 GHz to 1.785 GHz and / or a 1.850 GHz to 1.910 GHz operating frequency band, and the second frequency is within a 820 MHz to 920 MHz frequency band.

[0005] Optionally, said first resonator and said second resonator are in series resonance at said second frequency and a frequency of said first harmonic signal.

[0006] Optionally, the first impedance matcher includes a third inductor and a third capacitor connected in series.

[0007] Optionally, the third inductor and the third capacitor resonate at the first frequency.

[0008] Optionally, the first trap includes a fourth inductor and a fourth capacitor connected in series.

[0009] Optionally, the fourth inductor and the fourth capacitor resonate at a frequency of the second harmonic signal.

[0010] Optionally, said first harmonic signal is a third harmonic of said first frequency signal, said second harmonic signal is a second harmonic of said first frequency signal, and said first predetermined impedance is 50 ohms.

[0011] The present application further provides an RF front-end power amplifier circuit including any of the matching circuits described above and an RF power amplifier connected to the matching circuit.

[0012] The present application further provides a mobile communication device including any of the power amplifier circuits described above, or any of the matching circuits described above.

[0013] The present application further provides a chip including any of the power amplifier circuits described above, or any of the matching circuits described above.

[0014] By using the above matching circuit, power amplifier circuit, and mobile communication device, the harmonics of the in-band signal can be suppressed better. There is a good suppression effect on the second, third, and higher harmonics of the in-band signal. In addition, the matching circuit has a good suppression effect on low-frequency spurious noise. By using the matching circuit according to the present application, it is possible to kill two birds with one stone by suppressing harmonics and optimizing low-frequency spurious.

[0015] For example, current mobile communication devices generally need to process multiple mode signals, and generally need to process DCS1800 and / or PSC1900 signals as well as GSM frequency band signals. In the mobile device, the DCS1800 and / or PSC1900 signals are in-band signals for the power amplifier circuit that processes the DCS1800 and / or PSC1900 signals. The harmonic signals of the in-band signals and the GSM frequency band signals are the main interference sources. By using the matching circuit according to the present application, the interference effects of the above interference sources can be effectively suppressed. Moreover, the circuit has a simple structure and is easy to implement.

[0016] In order to more clearly describe the technical solutions in the embodiments of the present application, the following briefly introduces drawings required for the description of the embodiments. [Brief description of the drawings]

[0017] [Figure 1] 1 shows a schematic diagram of a topology structure of an RF front-end power amplifier circuit in the prior art; [Diagram 2] 1 illustrates an exemplary matching circuit according to an embodiment of the present application. [Diagram 3] 3 shows a transmission gain curve of the bandpass filter 11 in the matching circuit shown in FIG. [Figure 4] 3 shows a schematic diagram of another topology structure of the matching circuit shown in FIG. 2. [Diagram 5] 3A and 3B are schematic diagrams showing gain comparison waveforms in the cases where the matching circuit shown in FIG. 2 is cascaded with the power amplifier circuit shown in FIG. 1 and where it is not; [Figure 6] 1 shows a schematic topology diagram of an RF front-end power amplifier circuit according to another embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] FIG. 1 shows a schematic diagram of the topology structure of an RF front-end power amplifier circuit in the prior art.

[0019] As shown in FIG. 1, a conventional RF front-end power amplifier circuit consists of a power amplifier PA and a L 01 ~L 03 , C 01 ~C 04 , and a filter circuit consisting of L1 to L3.

[0020] Conventionally, mobile communication devices generally need to process multiple types of communication signals in an integrated manner. For example, mobile communication signals need to simultaneously process multiple mode signals including at least two in the DCS1800 (1.710 GHz to 1.785 GHz) operating frequency band, the PSC1900 (1.850 GHz to 1.910 GHz) operating frequency band, and the GSM (820 MHz to 920 MHz) operating frequency band.

[0021] 1 is a power amplifier circuit that processes DCS1800 (1.710 GHz to 1.785 GHz) and / or PSC1900 (1.850 GHz to 1.910 GHz), the in-band signal includes DCS1800 and / or PSC1900. Harmonics of the in-band signal and GSM frequency band signals are the main interference sources of the circuit.

[0022] The circuit shown in Fig. 1 has insufficient suppression against harmonic noise of in-band signals and low-frequency spurious noise including GSM frequency band signals, so it is difficult to meet the needs. Based on the circuit shown in Fig. 1, the present application provides a matching circuit shown in Fig. 2.

[0023] FIG. 2 illustrates an exemplary matching circuit according to an embodiment of the present application.

[0024] As shown in Fig. 2, the matching circuit 1000 may include an impedance matching device 12, a bandpass filter 11, and a trap 13. Optionally, the matching circuit may be provided at the output end of the RF power amplifier circuit. Optionally, the matching circuit 1000 may be connected to the output end of the circuit shown in Fig. 1.

[0025] The impedance matching box 12 may be used to match an impedance. At a first frequency, the impedance of the impedance matching box 12 is a first predetermined impedance. Optionally, the first predetermined impedance may be 50Ω. The first frequency may be within an operating frequency range of a power amplifier circuit connected to the matching circuit 1000. For example, it may be a center frequency of the operating frequency range. Optionally, the operating frequency range may include the DCS1800 (1.710 GHz to 1.785 GHz) frequency band and / or the PSC1900 (1.850 GHz to 1.910 GHz) frequency band. Optionally, the impedance matching box 12 may include an inductor L3 (third inductor) and a capacitor C3 (third capacitor) connected in series. Optionally, the inductor L3 and the capacitor C3 may resonate near the first frequency. Optionally, parameter values ​​of inductor L3 and capacitor C3 may be set according to parameters of inductor L4 and capacitor C4 such that the input impedance and output impedance of matching circuit 1000 become a first predetermined impedance.

[0026] As shown in FIG. 2, the bandpass filter 11 may be bridged between the front end of the impedance matching device 12 and ground. The bandpass filter 11 can pass a first frequency signal and suppress a noise signal near a first harmonic and a second frequency of the first frequency signal. The first harmonic may be a third harmonic of the first frequency signal. The second frequency may be within the GSM (820 MHz to 920 MHz) frequency band. Optionally, the bandpass filter 11 may include a resonator 111 and a resonator 112 connected in series. Optionally, the resonator 111 may include a capacitor C1 (first capacitor) and an inductor L1 (first inductor) connected in parallel. The resonator 112 may include a capacitor C2 (second capacitor) and an inductor L2 (second inductor) connected in series.

[0027] Optionally, resonator 111 may resonate at a frequency between the second frequency and the first harmonic frequency, which may be three times the first frequency. Resonator 112 may also resonate at a frequency between the second frequency and the first harmonic frequency. Optionally, resonator 111 and resonator 112 may resonate at the same frequency. Optionally, resonator 111 and resonator 112 may resonate in series at the second frequency and the first harmonic frequency. For example, the impedance of resonator 111 is:

number

[0028] The impedance of the resonator 112 is given by:

number

[0029]

number

[0030] The impedance of the bandpass filter 11 is

number

[0031] Clearly, the equation for ω

number

[0032] FIG. 3 shows a transmission gain curve of the bandpass filter 11 in the matching circuit shown in FIG.

[0033] As shown in FIG. 3, 11A1 is a transmission gain curve in which the resonator 111 is used as a filter alone. 11A2 is a transmission gain curve in which the resonator 112 is used as a filter alone. 11A is a transmission gain curve of the bandpass filter 11. As can be seen from FIG. 3, the bandpass filter 11 has a transmission gain of −20.598 dB at a frequency m6=800 MHz (near the second frequency). That is, the bandpass filter 11 has an attenuation of more than 20 dB for the 800 MHz frequency. The bandpass filter 11 has a transmission gain of −16.705 dB at a frequency m10=4.93 GHz and a transmission gain of −14.45 dB at a frequency m11=5.67 GHz. That is, the bandpass filter 11 has an attenuation of more than 14 dB in the frequency range of 4.93 to 5.67 GHz (near the first harmonic frequency). It can be seen that the bandpass filter 11 has a clear attenuation effect near the second frequency and near the first harmonic frequency.

[0034] As shown in FIG. 2, the trap 13 may be bridged between the back end of the impedance matching box 12 and ground. The trap 13 may cooperate with the impedance matching box 12 to perform impedance matching. It may also be used to suppress the second harmonic of the first frequency signal. Optionally, the second harmonic may be the second harmonic of the first frequency signal. The trap 13 may include a capacitor C4 (fourth capacitor) and an inductor L4 (fourth inductor) connected in series. Optionally, the capacitor C4 and the inductor L4 may resonate near the frequency of the second harmonic.

[0035] Optionally, a matching circuit 1000 may be provided between the output of the power amplifier and the antenna.

[0036] FIG. 4 shows a schematic diagram of another topology structure of the matching circuit shown in FIG.

[0037] Optionally, the matching circuit 1000 may further include a first matching unit (not shown). The first matching unit may be connected to a front end of the impedance matching box 12. The first matching unit may include an inductor L5 (a fifth inductor), an inductor L6 (a sixth inductor), an inductor L7 (a seventh inductor), and a capacitor C5 (a fifth capacitor) connected in series.

[0038] The first matching unit may further include an inductor L8 (eighth inductor) and a capacitor C6 (sixth capacitor) connected in series. The inductor L8 and the capacitor C6 connected in series may be bridged between a connection point between the inductor L5 and the inductor L6 and ground. The first matching circuit may further include an inductor L9 (ninth inductor) and a capacitor C7 (seventh capacitor) connected in series. The inductor L9 and the capacitor C6 connected in series may be bridged between a connection point between the inductor L6 and the inductor L7 ... 10(tenth inductor) and capacitor C8 (eighth capacitor). 10 And capacitor C8 may be bridged between the junction of inductor L7 and capacitor C5 and ground.

[0039] FIG. 5 shows schematic diagrams of gain comparison waveforms in the cases where the matching circuit shown in FIG. 2 is cascaded with the power amplifier circuit shown in FIG. 1 and where it is not.

[0040] As shown in FIG. 5, curve 141 is the gain curve of the circuit shown in FIG. 1, and curve 142 is the gain curve when the circuit shown in FIG. 1 is cascaded with matching circuit 1000.

[0041] 5, when frequency m is 1=1.7 GHz, curve 142 is attenuated by 1.098 dB with respect to curve 141, and when frequency m is 2=2 GHz, curve 142 is attenuated by 1.547 dB with respect to curve 141. In other words, for signals with a frequency range of 1.7 to 2 GHz (operating frequency range), the amount of attenuation by matching circuit 1000 is negligibly small.

[0042] 5, when the frequency is m3=920 MHz, the curve 142 is attenuated by 15.541 dB relative to the curve 141, and when the frequency is m3=820 MHz, the curve 142 is attenuated by 18.631 dB relative to the curve 141. That is, the matching circuit 1000 can attenuate a noise signal having a frequency range of 820 to 920 MHz (GSM signal) by 15 dB or more.

[0043] 5, when the frequency m8=3.4 GHz, curve 142 is attenuated by 72.667 dB relative to curve 141, and when the frequency m18=3.84 GHz, curve 142 is attenuated by 74.096 dB relative to curve 141. In other words, matching circuit 1000 can produce a suppression effect of 70 dB or more for harmonic noise in the frequency range of 3.4 to 3.84 GHz (secondary harmonic of the operating frequency).

[0044] 5, when the frequency m19 is 5.13 GHz, the curve 142 is attenuated by 69.872 dB relative to the curve 141, and when the frequency m20 is 5.73 GHz, the curve 142 is attenuated by 70.3 dB relative to the curve 141. In other words, the matching circuit 1000 can produce a suppression effect of about 70 dB against harmonic noise in the frequency range of 5.13 to 5.73 GHz (the third harmonic of the operating frequency).

[0045] FIG. 6 shows a schematic diagram of a topology structure of an RF front-end power amplifier circuit in another embodiment of the present application.

[0046] 6, the power amplifier circuit 2000 may include a power amplifier 21, a filter circuit 22, and a matching circuit 23. The filter circuit 22 and the matching circuit 23 are cascaded to the output end of the power amplifier 21. The filter circuit 22 and the power amplifier 21 constitute a RF front-end power amplifier circuit in the prior art. The matching circuit may be any of the matching circuits described above.

[0047] Optionally, the in-band signal processed by the power amplifier circuit 2000 may include a DCS1800 (1.710 GHz to 1.785 GHz) frequency band signal and / or a PSC1900 (1.850 GHz to 1.910 GHz) frequency band signal. The matching circuit 23 can enhance the suppression of the in-band signal against harmonics and against low-frequency noise including the GSM band.

[0048] The present application further provides a mobile communication device including any of the matching circuits described above or any of the power amplifier circuits described above. Optionally, the mobile communication device may include a mobile phone, a tablet, a laptop, etc. Optionally, the mobile communication device is capable of simultaneously processing GSM frequency band signals and DCS1800 (1.710GHz-1.785GHz) frequency band signals. Or, the mobile communication device is capable of simultaneously processing GSM frequency band signals and PSC1900 (1.850GHz-1.910GHz) frequency band signals.

[0049] The present application further provides a chip including any of the power amplifier circuits described above, or any of the matching circuits described above.

[0050] By using the above matching circuit, power amplifier circuit, and mobile communication device, it is possible to suppress harmonics of in-band signals better. It has a good suppression effect on the second, third, and higher harmonics of the in-band signal. In addition, the matching circuit has a good suppression effect on low-frequency spurious. By using the matching circuit according to the present application, it is possible to kill two birds with one stone by suppressing harmonics and optimizing low-frequency spurious.

[0051] For example, a conventional mobile communication device generally needs to process multiple mode signals, and generally needs to process DCS1800 and / or PSC1900 signals as well as GSM frequency band signals. In the mobile device, the DCS1800 and / or PSC1900 signals are in-band signals for a power amplifier circuit that processes the DCS1800 and / or PSC1900 signals. Harmonic signals of the in-band signals and GSM frequency band signals are major interference sources. By using the matching circuit according to the present application, the interference effects of the above interference sources can be effectively suppressed. Moreover, the circuit has a simple structure and is easy to implement.

[0052] The above describes the embodiments of the present application in detail, and the present specification describes the principles and embodiments of the present application by applying specific examples. However, the above description of the embodiments is only intended to help understand the method and core idea of ​​the present application. Furthermore, any changes or modifications made by those skilled in the art in the specific embodiments and application scope of the present application based on the idea of ​​the present application are within the scope of protection of the present application. As described above, the contents of the present specification should not be construed as limiting the present application.

Claims

1. A matching circuit for use in an RF front-end power amplifier, comprising: a first impedance matching box having an impedance equal to a first predetermined impedance at a first frequency; a first bandpass filter that is connected between a front end of the first impedance matching device and ground, and that passes a first frequency signal and suppresses at least one of a signal of a second frequency that is lower than the first frequency and a first harmonic signal of the first frequency signal; a first trap disposed between a back end of the first impedance matching box and ground, for suppressing a second harmonic signal of the first frequency signal; a first matching unit connected to a front end of the first impedance matching box; the first bandpass filter includes a first resonator and a second resonator connected in series, the first resonator including a first inductor and a first capacitor connected in parallel, and the second resonator including a second inductor and a second capacitor connected in series; the first matching unit includes a fifth inductor, a sixth inductor, a seventh inductor, and a fifth capacitor connected in series; The first alignment unit includes: an eighth inductor and a sixth capacitor connected in series between a connection point between the fifth inductor and the sixth inductor and ground; a ninth inductor and a seventh capacitor connected in series between a connection point between the sixth inductor and the seventh inductor and ground; a tenth inductor and an eighth capacitor connected in series across a connection point between the seventh inductor and the fifth capacitor and ground, the first frequency is within the 1.710 GHz to 1.785 GHz and / or 1.850 GHz to 1.910 GHz operating frequency band; The matching circuit is characterized in that the second frequency is within a frequency band of 820 MHz to 920 MHz.

2. 2. The matching circuit according to claim 1, wherein the first resonator and the second resonator resonate in series at the second frequency and a frequency of the first harmonic signal.

3. The matching circuit according to claim 1 , wherein the first impedance matching device includes a third inductor and a third capacitor connected in series.

4. 4. The matching circuit according to claim 3, wherein the third inductor and the third capacitor resonate at the first frequency.

5. 2. The matching circuit according to claim 1, wherein the first trap includes a fourth inductor and a fourth capacitor connected in series.

6. 6. The matching circuit according to claim 5, wherein the fourth inductor and the fourth capacitor resonate at a frequency of the second harmonic signal.

7. the first harmonic signal is a third harmonic of the first frequency signal; the second harmonic signal is a second harmonic of the first frequency signal; 2. The matching circuit of claim 1, wherein the first predetermined impedance is 50 ohms.

8. 1. An RF front-end power amplifier circuit, comprising: A matching circuit according to any one of claims 1 to 7; an RF power amplifier connected to the matching circuit.

9. A mobile communication device, A mobile communication device comprising the power amplifier circuit according to claim 8.

10. A mobile communication device, comprising: A mobile communication device comprising the matching circuit according to any one of claims 1 to 7.

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