A dual-mode power amplifier capable of switching working power and a mode switching method

Abstract

The present invention discloses a dual-mode power amplifier with switchable working power and a mode switching method. The power amplifier comprises: an input transformer, comprising a plurality of output taps, and an input coil is loaded with a signal to be amplified; an output transformer, comprising input taps matching the number of output taps of the input transformer, and the output coil amplifies the signal; a plurality of power amplification branches, each of the power amplification branches comprises an intermediate switch and a power amplification tube, and each of the output taps is connected through a power amplification branch and an input tap; the intermediate switch is configured with a control signal to turn on the power amplification tube connected in series with the intermediate switch so that N of the plurality of output taps of the input transformer are connected to the input tap of the output transformer through the power amplification branch, and the amplified signal is output after being transformed by the output transformer. The present invention improves the performance of the power amplifier and simplifies the process.

Description

[0001] This application is a divisional application of the invention patent application entitled: A dual-mode power amplifier with switchable working power and mode switching method, filed on December 7, 2018, and with application number: 2018114948633. Technical Field

[0002] The present invention relates to a power amplifier and a mode switching method, and in particular to a dual-mode power amplifier capable of switching working power and a mode switching method. Background Art

[0003] A power amplifier is a device that can amplify the voltage or power of an input signal. It is composed of electron tubes or transistors, power transformers and other electrical components. It is widely used in various devices such as communications, broadcasting, radar, television, and automatic control.

[0004] Output power and power conversion efficiency are two main performance indicators of power amplifiers. For most commonly used power amplifier categories (A / B / C / D / E / F / F -1 Its best power conversion efficiency corresponds to the maximum output power, and its power conversion efficiency will decrease when the output power is lower. Therefore, it is difficult for the traditional single power amplifier structure to achieve high power conversion efficiency at different output powers.

[0005] Since the maximum output power of the power amplifier and its corresponding optimal power conversion efficiency are determined by the load line of the power amplifier, in order to achieve high power conversion efficiency at different output powers, multiple groups of power amplifiers can be integrated into the system. Each group of power amplifiers uses a different load line, corresponding to a different maximum output power, and the corresponding power amplifier can be turned on according to power requirements when the system is working. The disadvantage of this method is that it is necessary to integrate two or even more groups of power amplifiers in a limited space, which not only increases the manufacturing / material cost, but is also often difficult to implement in engineering applications. Summary of the invention

[0006] In order to solve the problems existing in the prior art, one of the purposes of the present invention is to provide a dual-mode power amplifier with switchable operating power that can realize switching of a front-stage load line and an output-stage load line, thereby realizing maximum output power switching.

[0007] In order to achieve the purpose of the present invention, a dual-mode power amplifier with switchable operating power provided herein includes:

[0008] An input transformer, including a plurality of output taps, and an input coil is loaded with a signal to be amplified;

[0009] an output transformer, including input taps matching the number of output taps of the input transformer, and an output coil amplifying the signal;

[0010] An intermediate switch and a power amplifier tube, wherein the multiple output taps of the input transformer are connected to the input tap of the output transformer via the intermediate switch and the power amplifier tube respectively, and the intermediate switch is configured with a control signal to turn on the power amplifier tube connected in series with the intermediate switch so that one or more of the multiple output taps of the input transformer are connected to the input tap of the output transformer, and the output transformer outputs an amplified signal after voltage transformation; and

[0011] A first matching capacitor and a second matching capacitor, wherein the first matching capacitor and the second matching capacitor are connected in parallel between taps at both ends of the input coil of the output transformer and the ground.

[0012] Furthermore, a conversion switch is connected between the taps at both ends of the input coil of the output transformer and the first matching capacitor.

[0013] Furthermore, two or more of the intermediate switches and the conversion switches form a group and are integrated on a single SOI chip or a power amplifier chip.

[0014] Furthermore, two or more of the intermediate switches form a group and are integrated on a single SOI chip or a power amplifier chip.

[0015] Furthermore, it also includes an input matching circuit and a pre-stage amplifier, and the signal to be amplified loaded on the input coil of the input transformer is matched by the input matching circuit and amplified by the pre-stage amplifier before being loaded.

[0016] Furthermore, the input matching circuit includes an input filtering circuit.

[0017] Furthermore, it also includes an output matching circuit, and the amplified signal output by the output coil of the output transformer is output after passing through the output matching circuit.

[0018] Furthermore, the output matching circuit includes an output filtering circuit and a switch group. The amplified signal output by the output coil of the output transformer is filtered by the output filtering circuit in turn, loaded on the switch group, and outputted through the switch group.

[0019] Furthermore, the dual-mode power amplifier also includes a selection circuit mainly composed of a selection switch S and a capacitor C, and the selection circuit is connected in series between the taps at both ends of the output transformer input coil. Through the selection circuit, two groups of taps in the output transformer input coil taps can be selected to be turned on according to specific circumstances, thereby forming a high power on and a low power off, or a high power off and a low power on.

[0020] The beneficial effects of the present invention are as follows: the power amplifier provided by the present invention adopts a multi-tap input transformer, and by controlling the on / off of an intermediate switch connected to the tap, the switching of the front-stage load line and the output-stage load line is realized, so that the power amplifier forms different working states to achieve the best performance under different maximum output powers.

[0021] The conversion switch is used to control the capacitance of the matching capacitor and adjust the output stage load line, thereby further ensuring the performance of the power amplifier provided by the present invention.

[0022] It is easy to integrate the intermediate switch and the conversion switch into an independent chip by using CMOS / phemt / bihemt / SeGe / SOI and other processes, or integrate them into a power amplifier chip by using CMOS / phemt / bihemt / SeGe / SOI and other processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A principle block diagram of a power amplifier provided by the present invention;

[0024] Figure 2 A circuit diagram of a power amplifier according to the present invention;

[0025] Figure 3 A circuit schematic diagram of the bias circuit described in the present invention;

[0026] Figure 4 One of the circuit principle diagrams of the output matching circuit described in the present invention;

[0027] Figure 5 The second circuit schematic diagram of the output matching circuit described in the present invention;

[0028] Figure 6 The third circuit schematic diagram of the output matching circuit described in the present invention;

[0029] Figure 7 The fourth circuit schematic diagram of the output matching circuit described in the present invention;

[0030] Figure 8 The fifth circuit schematic diagram of the output matching circuit described in the present invention;

[0031] Fig. 9 The sixth circuit schematic diagram of the output matching circuit described in the present invention;

[0032] Fig.10 FIG7 is a seventh circuit schematic diagram of the output matching circuit described in the present invention;

[0033] Fig.11This is the eighth circuit schematic diagram of the output matching circuit described in the present invention. DETAILED DESCRIPTION

[0034] The technical solution claimed in this application is further described in detail in conjunction with the accompanying drawings and specific implementation methods.

[0035] The technical solution claimed in the present invention is a dual-mode power amplifier with switchable working power and a mode switching method based on the power amplifier, wherein the principle block diagram of the dual-mode power amplifier with switchable working power is as follows: Figure 1 As shown, it includes

[0036] An input transformer T1 includes a plurality of output taps, and a signal to be amplified is loaded on the input coil;

[0037] an output transformer T2, including input taps matching the number of output taps of the input transformer, and an output coil amplifying the signal;

[0038] An intermediate switch and a power amplifier tube, wherein the multiple output taps of the input transformer are connected to the input taps of the output transformer via the intermediate switch and the power amplifier tube, respectively. The intermediate switch is configured with a control signal to turn on the power amplifier tube connected in series with the intermediate switch so that one or more of the multiple output taps of the input transformer are connected to the input taps of the output transformer, and the amplified signal is output after voltage transformation by the output transformer; and

[0039] A first matching capacitor and a second matching capacitor, wherein the first matching capacitor and the second matching capacitor are connected in parallel between taps at both ends of the input coil of the output transformer and the ground.

[0040] The number of the input transformer output taps and the input taps of the output transformer in the power amplifier can be 2, 4, 6 or other numbers; the power amplifier tube described can be a field effect tube or a crystal triode. Here, the power amplifier disclosed in the present invention is further described by taking the input and output transformers as 4 taps and the power amplifier tube as a crystal field effect tube as an example. Figure 2As shown. The output coil of the input transformer T1 includes taps 1, 2, 3 and 4, and the input coil of the output transformer T2 matched therewith includes taps 5, 6, 7 and 8. Tap 1 is connected to the base of the power amplifier tube Q1 via the intermediate switch S1 and the capacitor C1, the collector of the power amplifier tube Q1 is connected to tap 5, and the emitter is grounded; tap 2 is connected to the base of the power amplifier tube Q2 via the intermediate switch S2 and the capacitor C2, the collector of the power amplifier tube Q2 is connected to tap 6, and the emitter is grounded; tap 3 is connected to the base of the power amplifier tube Q3 via the intermediate switch S3 and the capacitor C3, the collector of the power amplifier tube Q3 is connected to tap 7, and the emitter is grounded; tap 4 is connected to the base of the power amplifier tube Q4 via the intermediate switch S4 and the capacitor C4, the collector of the power amplifier tube Q4 is connected to tap 8, and the emitter is grounded; tap 5 and tap 8 are grounded via the first matching capacitor C5 and the second matching capacitor C6 respectively, and the two form a parallel relationship.

[0041] One end of the input coil of the input transformer T1 is connected to the power supply VCC1 and grounded via capacitor C9, and the other end is loaded with the signal to be amplified. The conduction of the intermediate switches S1~S4 is controlled by an external control signal; one end of the output coil of the output transformer T2 is grounded, and the other end outputs the amplified signal.

[0042] The working state of the power amplifier provided by the present invention is divided into the working state of the class E power amplifier and the working state of the class F power amplifier. -1 In the working state of the class E power amplifier, the signal to be amplified is loaded on the input coil of the input transformer T1, and the control signal is loaded on the intermediate switches S1~S4, so that the intermediate switch S1 and the intermediate switch S4 are turned on or the intermediate switch S2 and the intermediate switch S3 are turned on; when the intermediate switch S1 and the intermediate switch S4 are turned on, the power amplifier tube Q1 and the power amplifier tube Q4 are turned on, and the signal to be amplified is loaded on the tap 5 and the tap 8 of the input coil of the output transformer T2, and the load line is composed of the first matching capacitor C5 and the output transformer T2. At this time, the power amplifier is in the working state of the class E power amplifier.

[0043] When the loaded control signal turns on the intermediate switch S2 and the intermediate switch S3, the power amplifier tubes Q2 and Q3 are turned on, and the signal to be amplified is loaded on the tap 6 and the tap 7 of the input coil of the output transformer T2. Figure 2 The second matching capacitor C6 in the solid line rectangular frame, Figure 2 The inductance between tap 5 and tap 6 in the solid rectangular frame and the adjacent Figure 2 The inductance between tap 7 and tap 8 in the solid rectangular frame forms a third-order harmonic impedance. -1 Class A power amplifier working status.

[0044] In order to better adjust the load line of the power amplifier, a conversion switch S5 and a conversion switch S6 are added on the basis of the above solution. The conversion switch S5 is connected in series between the tap 1 and the first matching capacitor C5, and the conversion switch S6 is connected in series between the tap 8 and the first matching capacitor C5. The conduction of the conversion switch S5 and the conversion switch S6 is controlled by an external control signal, and the capacitance of the matching capacitor can be controlled by the conversion switch.

[0045] In addition, the dual-mode power amplifier provided by the present invention further comprises a selection circuit mainly composed of a selection switch S and a capacitor C, and the selection circuit is connected in series between the two end taps of the input coil of the output transformer.

[0046] In order to enable the power amplifier tube to amplify the signal voltage without distortion, the power amplifier provided by the present invention also includes a bias circuit. The circuit schematic diagram of the bias circuit is as follows: Figure 3 As shown, it includes bias branches equal to the number of power amplifier tubes, each bias branch includes an output terminal, and the output control signal is loaded on the control terminal of the power amplifier tube. Each bias branch includes a switch tube T1, a resistor R1, a resistor R2, a resistor R3, a capacitor C7, a diode D1 and a diode D2. The power supply terminal of the switch tube T1 is connected to an external control signal (such as a power supply) via the resistor R1, and the resistor R2 is connected to the output terminal of the switch tube T1; the control terminal of the switch tube T1 is grounded via the capacitor C7, and the control terminal of the switch tube T1 is also connected to the anode of the diode D1, the cathode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is grounded; the control terminal of the switch tube T1 is also connected to the external control signal via the resistor R3. Among them, the switch tube T1 can be a crystal triode or a field effect tube.

[0047] In order to ensure the stability of the signal loaded on the input transformer T1, the power amplifier also includes an input matching circuit and a pre-amplifier Q5 for filtering the signal to be amplified. The input matching circuit includes an input filter circuit, wherein the input filter circuit can adopt any existing capacitor filter circuit, inductor filter circuit, RC filter circuit and LC filter circuit. The input filter circuit used here includes capacitor C8, capacitor C10 and inductor L1. The first plate of capacitor C8 is used as an input end for loading the signal, and the second plate is connected to the control end of the pre-amplifier Q5 through capacitor C10. The second plate of capacitor C8 is also grounded through inductor L1. The power supply end of the pre-amplifier Q5 is grounded, and the output end is connected to the input coil of the input transformer T1. Among them, the pre-amplifier Q5 can adopt a crystal triode or a field effect tube.

[0048] In order to achieve the required bandwidth and harmonic suppression of the power amplifier, the power amplifier also includes an output matching circuit for filtering the signal output by the output transformer T2, which includes an output filter circuit and a switch group composed of a plurality of switches. The output filter circuit can be composed of capacitors and inductors to form any of the following: 1. Low-pass filter circuit, the circuit connection relationship of which is as follows Figure 4 As shown, it includes a capacitor C11, a capacitor C12, an inductor L2 and an inductor L3. One end of the inductor L2 is connected to the output coil of the output transformer T2 as an input end, and the other end is connected to the switch group through the inductor L3; the end of the inductor L2 connected to the inductor L3 is also grounded through the capacitor C11, and the end of the inductor L3 connected to the switch group is grounded through the capacitor C12.

[0049] The high-pass and low-pass circuits have the following circuit connections: Figure 5 As shown, it includes a capacitor C13, an inductor L4, an inductor L5 and a capacitor C14. The first plate of the capacitor C13 is connected to the output coil of the output transformer T2 as an input end, and the second plate is connected to the switch group through the inductor L5; the second plate of the capacitor C13 is also grounded through the inductor L4, and the end of the inductor L5 connected to the switch group is grounded through the capacitor C14.

[0050] The low-pass notch circuit has the following circuit connection relationship: Figure 6 As shown, it includes capacitor C15, capacitor C16, inductor L6, inductor L7, inductor L8 and inductor L9. One end of the inductor L6 is connected to the output coil of the output transformer T2 as an input end, and the other end is connected to the switch group through the inductor L7; the end of the inductor L6 connected to the inductor L7 is also grounded through the capacitor C15 and the inductor L8, and the end of the inductor L7 connected to the switch group is grounded through the capacitor C16 and the inductor L9.

[0051] The high-pass and low-pass notch circuits have the following circuit connections: Figure 7 As shown, it includes an inductor L10, an inductor L11, an inductor L12, a capacitor C17 and a capacitor C18; one end of the capacitor C17 is connected to the output coil of the output transformer T2 as an input end, and the other end is connected to the switch group through the inductor L11; the end of the capacitor C17 connected to the inductor L11 is also grounded through the inductor L10, and the end of the inductor L11 connected to the switch group is grounded through the inductor L12 and the capacitor C18.

[0052] The switch group described in the above four filter circuits can be composed of 4, 6, 8 or other number of switches. The switch group used here is composed of switches S7 to S11. Each switch serves as an output and its on-off is controlled by an external control signal. The switches constituting the switch group can be integrated on a separate chip, and its process can be selected from SOI / CMOS / PHEMT / BIHEMT / SeGe, etc.

[0053] In addition, the output matching circuit described in this application may adopt one of the following structures in addition to the above structures:

[0054] A. Figure 8 As shown, the output matching circuit includes inductor L13, inductor L14, inductor L15, inductor L16, inductor L17, inductor L18, capacitor C19, capacitor C20, capacitor C21, switch group A, switch group B, independent switch S12 and independent switch S13. One end of the inductor L13 is connected to the output coil of the output transformer T2 as an input end, and the other end is connected to the switch group A and switch group B through the inductor L15 and the inductor L16 respectively; one end of the inductor L13 connected to the inductor L15 and the inductor L16 is also grounded through the capacitor C19 and the inductor L14; the switch group A is also grounded through the independent switch S12, the capacitor C20 and the inductor L17, and the switch group B is also grounded through the independent switch S13, the capacitor C21 and the inductor L18. The switch group A and the switch group B are composed of a number of switches controlled by external control signals, each switch is used as an output, and the independent switch S12 and the independent switch S13 are controlled by the external control signal.

[0055] B. Fig. 9 As shown, the output matching circuit includes capacitor C29, inductor L14, inductor L15, inductor L16, inductor L17, inductor L18, capacitor C20, capacitor C21, switch group A, switch group B, independent switch S12 and independent switch S13. The first plate of capacitor C29 is connected to the output coil of output transformer T2 as an input end, and the second plate is connected to switch group A and switch group B through inductor L15 and inductor L16 respectively; the second plate of capacitor C29 is also grounded through inductor L14; switch group A is also grounded through independent switch S12, capacitor C20 and inductor L17, and switch group B is also grounded through independent switch S13, capacitor C21 and inductor L18. Wherein switch group A and switch group B are composed of a plurality of switches controlled by external control signals, each switch is used as one output, and independent switch S12 and independent switch S13 are controlled by external control signals.

[0056] C. Fig.10As shown, it includes capacitors C22 to C26, inductor L19, switch group A, switch group B, independent switch S12 and independent switch S13. The first plate of capacitor C12 is connected to the output coil of output transformer T2 as the input end, and the other end is connected to switch group A and switch group B through capacitor C23 and capacitor C24 respectively; one end of capacitor C22 connected to capacitor C23 and capacitor C24 is also grounded through inductor L19; switch group A is also grounded through independent switch S12 and capacitor C25, and switch group B is also grounded through independent switch S13 and capacitor C26. Wherein switch group A and switch group B are composed of a number of switches controlled by external control signals, each switch is used as one output, and independent switch S12 and independent switch S13 are controlled by external control signals.

[0057] D. Fig.11 As shown, it includes capacitor C27, capacitor C28, inductor L20, switch group C, independent switch S14 and independent switch S15. The output end of output transformer T2 is grounded through independent switch S14 and capacitor C27. The output end of output transformer T2 is also connected to switch group C through inductor L20. One end of inductor L20 connected to switch group C is also grounded through independent switch S15 and capacitor C28. Switch group C includes a plurality of switches controlled by external control signals, each of which serves as one output; the plurality of switches, independent switch S14 and independent switch S15 constituting switch group C can be independently set or integrated on an independent SOI chip. Among them, capacitor C27 and capacitor C28 constitute a trap circuit. In addition to the capacitor C27 and capacitor C28 described in this application, any existing trap circuit can also be used, such as replacing capacitor C27 and capacitor C28 with inductors, or connecting inductors in series on the branches where capacitor C27 and capacitor C28 are located to form a capacitor + inductor series circuit.

[0058] The switches constituting the switch group A and the switch group B, the independent switch S12 and the independent switch S13 described in A, B and C above may be independently provided or integrated on an independent SOI chip.

[0059] The intermediate switches and conversion switches described in the present application can be independently set, or they can be integrated into an independent SOI chip in groups of two or more, or all switches as a group, such as the intermediate switch S1 and the intermediate switch S4 as a group, the switch S2 and the intermediate switch S3 as a group, the conversion switch S5 and the conversion switch S6 as a group, or the intermediate switches S1 to S4 as a group, or the intermediate switches S1 to S4, the conversion switch S5 and the conversion switch S6 as a group, or other combinations.

[0060] The dual-mode power amplifier provided by the present invention can be a distributed circuit structure, or all components can be integrated on a chip using bihemt / SOI / phemt / CMOS / SeGe and other processes to form an integrated circuit; it can also be a structure in which part of the components are integrated on a chip and the other part of the components are integrated on a chip, and the chips are connected by signal lines, for example, the intermediate switches are integrated as a group of two or more than two or all switches on an independent SOI chip, the conversion switches are integrated as a group of two or more than two or all switches on an independent SOI chip, the output matching circuit, the input matching circuit, the preamplifier, the input transformer and the output transformer are integrated on an independent SOI chip, and the independent SOI chips are connected by signal lines.

[0061] The input transformer T1 and the output transformer T2 described in the present invention may adopt any existing transformers, and a balanced-unbalanced transformer (Balun) is adopted here.

[0062] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Any modification or equivalent substitution made to the technical solution of the present invention by ordinary technicians in this field shall be included in the scope of the claims of the present invention as long as it does not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A dual-mode power amplifier with switchable operating power, characterized in that: The power amplifier includes: An input transformer, including a plurality of output taps, and an input coil is loaded with a signal to be amplified; an output transformer, including input taps matching the number of output taps of the input transformer, and an output coil amplifying the signal; An intermediate switch and a power amplifier tube, each of the output taps is connected to one of the input taps via the intermediate switch and the power amplifier tube; The intermediate switch is configured with a control signal to turn on the power amplifier tube connected in series therewith so that N of the multiple output taps of the input transformer are connected to the input taps of the output transformer through the intermediate switch and the power amplifier tube, and an amplified signal is output after being transformed by the output transformer, wherein N is an even number.

2. The dual-mode power amplifier with switchable operating power according to claim 1, characterized in that , the intermediate switch and the power amplifier tube are respectively configured as four; the input transformer includes four output taps, and the output transformer includes four input taps; The intermediate switch is configured with a control signal to turn on the power amplifier tube connected in series with it so that two of the four output taps of the input transformer are connected to the input taps of the output transformer through the intermediate switch and the power amplifier tube, and the amplified signal is output after being transformed by the output transformer.

3. The dual-mode power amplifier with switchable operating power according to claim 2, characterized in that: It also includes a first matching capacitor and a second matching capacitor, wherein the first matching capacitor and the second matching capacitor are connected in parallel between taps at both ends of the input coil of the output transformer and the ground.

4. The dual-mode power amplifier with switchable operating power according to claim 3, characterized in that: A conversion switch is connected between the taps at both ends of the input coil of the output transformer and the first matching capacitor.

5. The dual-mode power amplifier with switchable operating power according to claim 1 or 2, characterized in that: It also includes an output matching circuit, which includes an output filtering circuit and a switch group. The amplified signal output by the output coil of the output transformer is filtered by the output filtering circuit in turn, loaded on the switch group, and outputted through the switch group.

6. The dual-mode power amplifier with switchable operating power according to claim 5, characterized in that: The switch group includes an input end and multiple output ends. The amplified signal output by the output coil of the output transformer is filtered by the output filter circuit in sequence and then loaded on the input end of the switch group, and output through at least one output end of the switch group.

7. The dual-mode power amplifier with switchable operating power according to claim 6, characterized in that: The switch group is composed of M switches, each of which serves as an output, and the on-off of each switch is controlled by an external control signal, wherein M is an even number.

8. The dual-mode power amplifier with switchable operating power according to claim 7, characterized in that: Each switch of the switch group is independently configured, or integrated on a separate chip.

9. The dual-mode power amplifier with switchable operating power according to claim 1, characterized in that: It also includes a selection circuit mainly composed of a selection switch S and a capacitor C, and the selection circuit is connected in series between the two end taps of the input coil of the output transformer.

10. The mode switching method of a dual-mode power amplifier with switchable operating power according to any one of claims 1 to 9, characterized in that: The method loads a signal to be amplified onto the input coil of the input transformer, loads a control signal onto the intermediate switch to turn on some of the intermediate switches, turns on the power amplifier tubes connected in series with the turned-on intermediate switches, thereby connecting N of the multiple output taps of the input transformer to the input taps of the output transformer, and outputs the amplified signal after being transformed by the output transformer, wherein N is an even number.

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