Numerical control variable gain amplifier
By connecting a switching transistor to the source of the RF transistor and using the switching transistor to control the on/off state of the RF transistor, the problem of gain control accuracy caused by parasitic parameters in traditional digitally controlled variable gain amplifiers is solved, achieving gain control with higher accuracy and lower circuit complexity.
Patent Information
- Application Number
- CN202422876757.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2034-11-25
AI Technical Summary
Traditional digitally controlled variable gain amplifiers require individual control of the gate voltage of each branch RF tube, which results in a large number of parasitic parameters in the RF connection wiring and reduces the gain control accuracy.
By connecting a switching transistor to the source of the RF transistor and controlling the switching transistor to turn the RF transistor on or off, the DC blocking capacitor is avoided, and the gain control is achieved by controlling the source voltage of the RF transistor using the switching transistor.
It improves gain control accuracy, reduces circuit area and complexity, and optimizes overall performance through the smaller gain variation range of the two-stage variable gain amplifier.
Smart Images
Figure CN223462995U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to gain control technical field especially relates to a numerical control variable gain amplifier. BACKGROUND
[0002] Variable Gain Amplifier (VGA) is a kind of amplifier that can adjust gain according to digital control signal, is widely used in various radio frequency transceiver systems, and its performance directly influences the performance of receiver. Figure 1 As shown in the figure, the numerical control variable gain amplifier includes four radio frequency tubes M1, M2, M3, M4, and a blocking capacitor is arranged in front of the gate of each radio frequency tube, which will cause more parasitic parameters to be generated in the winding of radio frequency connection line, and then additional phase shift is generated, thereby reducing the gain control precision. SUMMARY
[0003] The utility model discloses a numerical control variable gain amplifier, which overcomes the problems of the prior art.
[0004] The utility model discloses a numerical control variable gain amplifier, which overcomes the problems of the prior art.
[0005] In an example, the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded.
[0006] In an example, the radio frequency tube and the switch tube are both transistors.
[0007] In an example, the gain amplifier includes a first branch, a second branch, a third branch and a fourth branch, the first branch includes a first radio frequency tube and a first switch tube, the source of the first radio frequency tube is connected to the drain of the first switch tube, and the source of the first switch tube is grounded.
[0008] The gate of the first radio frequency tube, the gate of the second radio frequency tube, the gate of the third radio frequency tube, and the gate of the fourth radio frequency tube are interconnected, the drain of the first radio frequency tube, the drain of the second radio frequency tube, the drain of the third radio frequency tube, and the drain of the fourth radio frequency tube are interconnected, and the gate of the first switch tube, the gate of the second switch tube, the gate of the third switch tube, and the gate of the fourth switch tube are connected to the controller.
[0009] In an example, the gain amplifier comprises two or more gain amplification modules, and the gain amplification modules are matched through transformers;
[0010] Each gain amplification module comprises a plurality of gain amplification sub-modules, each gain amplification sub-module comprises a plurality of branches, each branch comprises a radio frequency tube, the source of the radio frequency tube in each branch is connected to a switch tube, the gates of the switch tubes are connected to the controller, the sources of the radio frequency tubes in each branch are connected to the drains of the switch tubes in the current branch, the sources of the switch tubes are grounded, the gates of the radio frequency tubes of each branch are interconnected, the drains of the radio frequency tubes of each branch are interconnected, the gates of the radio frequency tubes in each gain amplification sub-module are interconnected, and the drains of the radio frequency tubes in each gain amplification sub-module are interconnected.
[0011] In an example, the gain amplifier comprises a primary gain amplification module and a secondary gain amplification module, and the primary gain amplification module and the secondary gain amplification module are matched through transformers;
[0012] The primary gain amplification module comprises a first gain amplification sub-module a, a first gain amplification sub-module b, a first gain amplification sub-module c, and a first gain amplification sub-module d, each first gain amplification sub-module comprises four branches, each branch comprises a radio frequency tube, the source of the radio frequency tube in each branch is connected to a switch tube, the gates of the switch tubes are connected to the controller, the sources of the radio frequency tubes in each branch are connected to the drains of the switch tubes in the current branch, the sources of the switch tubes are grounded, the gates of the radio frequency tubes of each branch are interconnected, the drains of the radio frequency tubes of each branch are interconnected, the gates of the radio frequency tubes in the first gain amplification sub-module a and the first gain amplification sub-module b are interconnected and then connected to the positive electrode end of the secondary side of an input transformer TR1, the gates of the radio frequency tubes in the first gain amplification sub-module c and the first gain amplification sub-module d are interconnected and then connected to the negative electrode end of the secondary side of the input transformer TR1, the primary side of the input transformer TR1 is connected to an input voltage, the drains of the radio frequency tubes in the first gain amplification sub-module a and the first gain amplification sub-module c are interconnected and then connected to the positive electrode end of the primary side of a first intermediate stage transformer TR2, and the drains of the radio frequency tubes in the first gain amplification sub-module b and the first gain amplification sub-module d are interconnected and then connected to the negative electrode end of the primary side of the first intermediate stage transformer TR2.
[0013] The second gain amplification module comprises a second gain amplification submodule a, a second gain amplification submodule b, a second gain amplification submodule c and a second gain amplification submodule d, each of which comprises a plurality of branches, each of which comprises a radio frequency tube, the source of the radio frequency tube in each branch is connected to a switch tube, and the gate of each switch tube is connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes in each branch are connected to each other, and the drains of the radio frequency tubes in each branch are connected to each other; the gates of the radio frequency tubes in the second gain amplification submodule a and the second gain amplification submodule b are connected to each other and then connected to the positive electrode end of the secondary side of a first intermediate stage transformer TR2, and the gates of the radio frequency tubes in the second gain amplification submodule c and the second gain amplification submodule d are connected to each other and then connected to the negative electrode end of the secondary side of the first intermediate stage transformer TR2; the drains of the radio frequency tubes in the second gain amplification submodule a and the second gain amplification submodule c are connected to each other and then connected to the positive electrode end of the primary side of a third intermediate stage transformer TR3, and the drains of the radio frequency tubes in the second gain amplification submodule b and the second gain amplification submodule d are connected to each other and then connected to the negative electrode end of the primary side of the third intermediate stage transformer TR3, and the secondary side of the third intermediate stage transformer TR3 is used as an output.
[0014] It should be further explained that the technical features corresponding to the above examples can be combined or replaced to form new technical solutions.
[0015] Compared with the prior art, the utility model has the beneficial effects that:
[0016] The switch tube is added to the source of the radio frequency tube, the switch tube in each branch is controlled to be turned on or turned off, the radio frequency tube is turned on or turned off, the radio frequency tube is controlled to be turned on or turned off by using the switch tube to control the source voltage of the radio frequency tube, the direct current blocking capacitor is avoided, more parasitic parameters are avoided, the gain control precision is ensured, and the circuit area and complexity can be reduced.
[0017] Further, the application uses the small gain variation range of the second variable gain amplifier to compensate the overall gain step at the cost of a small gain additional phase shift, and the overall performance can be optimized. BRIEF DESCRIPTION OF DRAWINGS
[0018] The specific embodiments of the utility model will be further explained in detail below in combination with the drawings, the drawings explained herein are used to provide further understanding of the application, and constitute a part of the application, the same reference numerals are used to represent the same or similar parts in the drawings, the schematic embodiments of the application and the explanation thereof are used to explain the application, and do not constitute improper limitation on the application.
[0019] Figure 1 It is the circuit principle diagram of the prior numerical control variable gain amplifier;
[0020] Figure 2 The module control variable gain amplifier circuit principle diagram provided by the utility model for an example;
[0021] Figure 3 The equivalent circuit diagram when the switch tube is turned on and turned off provided by the utility model for an example;
[0022] Figure 4 The single-stage variable gain amplification simulation result diagram provided by the utility model for an example;
[0023] Figure 5 The two-stage variable gain amplifier circuit principle diagram provided by the utility model for an example;
[0024] Figure 6 The simulation gain range schematic diagram provided by the utility model for an example;
[0025] Figure 7 The two-stage variable gain amplification simulation schematic diagram provided by the utility model for an example. DETAILED DESCRIPTION
[0026] The technical solutions of the utility model will be described clearly and completely below in combination with the drawings, obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without making creative efforts belong to the protection scope of the utility model.
[0027] In the description of the utility model, it needs to be explained that the directions or position relations of "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like described based on the drawings are only for the convenience of describing the utility model and simplifying the description, and cannot be understood as limiting the utility model. Therefore, it cannot be understood as limiting the utility model. In addition, ordinal numbers (for example, "first and second", "first to fourth" and the like) are used for distinguishing objects, and are not limited to the order, and cannot be understood as indicating or implying relative importance.
[0028] In the description of the utility model, it needs to be explained that, unless otherwise explicitly specified and limited, "mounting", "connecting" and "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For the person skilled in the art, the specific meaning of the above-mentioned terms in the utility model can be understood according to the specific circumstances.
[0029] In addition, the technical features involved in the different embodiments of the utility model described below can be combined with each other as long as they do not conflict with each other.
[0030] In an example, a digitally controlled variable gain amplifier includes a plurality of branches, each branch including a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller. The radio frequency tube is a transistor for amplifying radio frequency signals, having high frequency response and low noise characteristics. The switch tube is a transistor used to control the on-off of the signal in the gain amplifier. The controller can be a single-chip microcomputer, FPGA, CPLD, etc.
[0031] Further, the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes of each branch are connected to each other for receiving an input voltage Vin; the drains of the radio frequency tubes of each branch are connected to each other and output an output voltage Vout.
[0032] More specifically, as shown in Figure 2 The gain amplifier includes a first branch, a second branch, a third branch and a fourth branch. The first branch includes a first radio frequency tube M1 and a first switch tube SW1, the source of the first radio frequency tube M1 being connected to the drain of the first switch tube SW1, and the source of the first switch tube SW1 being grounded. The second branch includes a second radio frequency tube M2 and a second switch tube SW2, the source of the second radio frequency tube M2 being connected to the drain of the second switch tube SW2, and the source of the second switch tube SW2 being grounded. The third branch includes a third radio frequency tube M3 and a third switch tube SW3, the source of the third radio frequency tube M3 being connected to the drain of the third switch tube SW3, and the source of the third switch tube SW3 being grounded. The fourth branch includes a fourth radio frequency tube M4 and a fourth switch tube SW3, the source of the fourth radio frequency tube M4 being connected to the drain of the fourth switch tube SW3, and the source of the fourth switch tube SW3 being grounded.
[0033] The gates of the first radio frequency tube M1, the second radio frequency tube M2, the third radio frequency tube M3 and the fourth radio frequency tube M4 are connected to each other, the drains of the first radio frequency tube M1, the second radio frequency tube M2, the third radio frequency tube M3 and the fourth radio frequency tube M4 are connected to each other, and the gates of the first switch tube SW1, the second switch tube SW2, the third switch tube SW3 and the fourth switch tube SW3 are independently connected to the controller, i.e. the gates of the first switch tube SW1, the second switch tube SW2, the third switch tube SW3 and the fourth switch tube SW3 are respectively connected to different control interfaces (such as I / O ports) of the controller, so as to realize independent control of the controller over the switch tubes.
[0034] In this example, the on-off control of each tube of the module control variable gain amplifier is independent. As shown in Figure 3 When the switch tube SW1 is turned on, at this time the switch tube SW1 is equivalent to the resistance R on , the gate-source voltage of the radio frequency tube M1 is V gs1 =V g -I ds1 *R on (R on →0), V gs1 >V th , V g represents the gate voltage of the radio frequency tube M1; I ds1 represents the drain current of the switch tube SW1; R on represents the equivalent resistance of the switch tube SW1; V gs1 represents the gate-source voltage of the radio frequency tube M1; V th represents the threshold voltage of the radio frequency tube M1, at this time the radio frequency tube M1 is turned on because the gate-source voltage of the radio frequency tube M1 is greater than its threshold voltage; when the switch tube SW1 is turned off, at this time the switch tube SW1 is equivalent to the resistance R off , the gate-source voltage of the radio frequency tube M1 is V gs1 =V g -I ds1 *R off (R off →+∞), V gs1 <V th , at this time the radio frequency tube M1 is turned off because the gate-source voltage of the radio frequency tube M1 is less than its threshold voltage, and the working mode of other branches is similar. Because the working state of each radio frequency tube is controlled by controlling the source voltage Vs of the radio frequency tube, the tail tube of the switch tube is used to control the source voltage of the radio frequency tube, so that the use of the blocking capacitor is avoided, and therefore the blocking capacitor of the gate voltage can be cancelled.
[0035] Further, as shown in Figure 4 The utility model variable gain amplifier each branch includes a radio frequency tube and a switch tube respectively, forms a level gain amplification, for single level variable gain amplifier, along with the gain change increases, the gain step increases significantly.
[0036] In an example, the gain amplifier comprises two or more gain amplification modules, each gain amplification module being transformer-coupled to another gain amplification module; each gain amplification module comprises a plurality of gain amplification sub-modules, each gain amplification sub-module comprising a plurality of branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gate of the radio frequency tube of each branch is connected to the gate of the radio frequency tube of another branch, and the drain of the radio frequency tube of each branch is connected to the drain of the radio frequency tube of another branch; the gate of the radio frequency tube of each gain amplification sub-module is connected to the gate of the radio frequency tube of another gain amplification sub-module, and the drain of the radio frequency tube of each gain amplification sub-module is connected to the drain of the radio frequency tube of another gain amplification sub-module. The control bits of a later-stage gain amplification module are less than those of an earlier-stage gain amplification module, i.e., the later-stage gain amplification module has fewer branches than the earlier-stage gain amplification module.
[0037] Optionally, as shown in FIG. 1, the gain amplifier comprises a first gain amplification module and a second gain amplification module, the first gain amplification module being transformer-coupled to the second gain amplification module. Figure 5
[0038] Specifically, the first gain amplification module comprises four first gain amplification sub-modules, i.e., a first gain amplification sub-module a (GA1a), a first gain amplification sub-module b (GA1b), a first gain amplification sub-module c (GA1c), and a first gain amplification sub-module d (GA1d), each first gain amplification sub-module comprising four branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gate of the radio frequency tube of each branch is connected to the gate of the radio frequency tube of another branch, and the drain of the radio frequency tube of each branch is connected to the drain of the radio frequency tube of another branch; the gate of the radio frequency tube of each first gain amplification sub-module is connected to the gate of the radio frequency tube of another first gain amplification sub-module, specifically, the gate of the radio frequency tube of the first gain amplification sub-module a and the first gain amplification sub-module b is connected to the secondary side P of the input transformer TR1 after being connected to each other, the gate of the radio frequency tube of the first gain amplification sub-module c and the first gain amplification sub-module d is connected to the secondary side N of the input transformer TR1 after being connected to each other, and the primary side of the input transformer TR1 is connected to an input voltage; the drain of the radio frequency tube of each first gain amplification sub-module is connected to the drain of the radio frequency tube of another first gain amplification sub-module, specifically, the drain of the radio frequency tube of the first gain amplification sub-module a and the first gain amplification sub-module c is connected to the primary side P of the first intermediate-stage transformer TR2 after being connected to each other, and the drain of the radio frequency tube of the first gain amplification sub-module b and the first gain amplification sub-module d is connected to the primary side N of the first intermediate-stage transformer TR2 after being connected to each other.
[0039] The second-stage gain amplification module comprises four second-stage gain amplification sub-modules, namely a second-stage gain amplification sub-module a (GA2a), a second-stage gain amplification sub-module b (GA2b), a second-stage gain amplification sub-module c (GA2c) and a second-stage gain amplification sub-module d (GA2d), each of the second-stage gain amplification sub-modules comprises two branches, each of the branches comprises a radio frequency tube, the source of the radio frequency tube in each of the branches is connected to a switch tube, the gate of each of the switch tubes is connected to the controller, the source of the radio frequency tube in each of the branches is connected to the drain of the switch tube in the current branch, the source of the switch tube is grounded, the gates of the radio frequency tubes of each of the branches are connected to each other, the drains of the radio frequency tubes of each of the branches are connected to each other, the gates of the radio frequency tubes in each of the second-stage gain amplification sub-modules are connected to each other, specifically, the gates of the radio frequency tubes in the second-stage gain amplification sub-modules a and b are connected to each other and then connected to the secondary side P end of the first intermediate-stage transformer TR2, the gates of the radio frequency tubes in the second-stage gain amplification sub-modules c and d are connected to each other and then connected to the secondary side N end of the first intermediate-stage transformer TR2, the drains of the radio frequency tubes in each of the second-stage gain amplification sub-modules are connected to each other, specifically, the drains of the radio frequency tubes in the second-stage gain amplification sub-modules a and c are connected to each other and then connected to the primary side P end of the third intermediate-stage transformer TR3, the drains of the radio frequency tubes in the second-stage gain amplification sub-modules b and d are connected to each other and then connected to the primary side N end of the third intermediate-stage transformer TR3, and the secondary side of the third intermediate-stage transformer TR3 serves as an output.
[0040] The variable gain amplifier of the example can form two-stage amplification through the first-stage gain amplification module and the second-stage gain amplification module, and a first-stage variable gain amplifier is also introduced in the second stage, and the difference lies in that only two control bits are used in the second-stage gain amplification module, and the gain variation range is reduced compared to the first stage, and the low gain state can be compensated by changing the gain of the second-stage amplifier.
[0041] Further, the simulation of the analog control two-stage gain amplifier is carried out, and a simulation gain range result graph is as shown in Figures 6-7 Figure 6 7 In the simulation gain range result graph, the horizontal coordinate is frequency, the unit is GHz, and the vertical coordinate is gain, the unit is dB. Figure 6 According to the simulation gain range result graph, it can be known that the analog control variable gain amplifier of the example can realize a gain adjustment range of ±6dB. Figure 7 According to the simulation gain range result graph, it can be known that the analog control variable gain amplifier of the example still maintains a small gain step in the low gain state.
[0042] The utility model discloses a kind of variable gain amplifiers of the scheme of using radio frequency tube switching characteristic control radio frequency tube on-off, to avoid using direct-current capacitor with simple circuit structure, simplify circuit layout complexity, can be widely applied in variable gain amplifier design.Meanwhile, the utility model scheme is based on the transmission characteristic when radio frequency tube switch is used, so it can be used to all CMOS technology, with higher reliability.
[0043] In an example, each branch includes two or more switching tubes, adjacent switching tubes are connected through the source, drain of each switching tube, namely the source of the former switching tube is connected with the drain of the latter switching tube, the gate of each switching tube is connected to the controller, and the source of the last switching tube is grounded, so as to realize multi-stage gain amplification.
[0044] The above detailed description of the embodiments is a detailed explanation of the utility model, and cannot be determined that the embodiments of the utility model are limited to these descriptions. For ordinary skilled in the art to which the utility model belongs, without departing from the concept of the utility model, a number of simple deductions and substitutions can be made, and all should be regarded as belonging to the protection scope of the utility model.
Claims
1. A digitally controlled variable gain amplifier, characterized by: The gain amplifier comprises several branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; The source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes of the branches are connected to each other, and the drains of the radio frequency tubes of the branches are connected to each other.
2. The digitally controlled variable gain amplifier of claim 1, wherein: The radio frequency tube and the switch tube are both transistors.
3. The digitally controlled variable gain amplifier of claim 1, wherein: The gain amplifier comprises a first branch, a second branch, a third branch and a fourth branch, the first branch comprising a first radio frequency tube and a first switch tube, the source of the first radio frequency tube being connected to the drain of the first switch tube, and the source of the first switch tube being grounded; the second branch comprising a second radio frequency tube and a second switch tube, the source of the second radio frequency tube being connected to the drain of the second switch tube, and the source of the second switch tube being grounded; the third branch comprising a third radio frequency tube and a third switch tube, the source of the third radio frequency tube being connected to the drain of the third switch tube, and the source of the third switch tube being grounded; the fourth branch comprising a fourth radio frequency tube and a fourth switch tube, the source of the fourth radio frequency tube being connected to the drain of the fourth switch tube, and the source of the fourth switch tube being grounded; The gates of the first radio frequency tube, the second radio frequency tube, the third radio frequency tube and the fourth radio frequency tube are interconnected, the drains of the first radio frequency tube, the second radio frequency tube, the third radio frequency tube and the fourth radio frequency tube are interconnected, and the gates of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all connected to the controller.
4. The digitally controlled variable gain amplifier of claim 1, wherein: The gain amplifier comprises two or more gain amplification modules, and the gain amplification modules are matched through transformers; The gain amplification module comprises several gain amplification sub-modules, each gain amplification sub-module comprising several branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes of the branches are connected to each other, and the drains of the radio frequency tubes of the branches are connected to each other; the gates of the radio frequency tubes in each gain amplification sub-module are connected to each other, and the drains of the radio frequency tubes in each gain amplification sub-module are connected to each other.
5. The digitally controlled variable gain amplifier of claim 4, wherein: The gain amplifier comprises a primary gain amplification module and a secondary gain amplification module, and the primary gain amplification module and the secondary gain amplification module are matched through transformers; The first-stage gain amplification module comprises first gain amplification sub-modules a, b, c and d, each of which comprises four branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes in each branch are connected to each other, and the drains of the radio frequency tubes in each branch are connected to each other; the gates of the radio frequency tubes in the first gain amplification sub-modules a and b are connected to each other and then connected to the positive terminal of the secondary side of an input transformer TR1, the gates of the radio frequency tubes in the first gain amplification sub-modules c and d are connected to each other and then connected to the negative terminal of the secondary side of the input transformer TR1, and the primary side of the input transformer TR1 is connected to an input voltage; the drains of the radio frequency tubes in the first gain amplification sub-modules a and c are connected to each other and then connected to the positive terminal of the primary side of a first intermediate-stage transformer TR2, and the drains of the radio frequency tubes in the first gain amplification sub-modules b and d are connected to each other and then connected to the negative terminal of the primary side of the first intermediate-stage transformer TR2; The second-stage gain amplification module comprises second gain amplification sub-modules a, b, c and d, each of which comprises two branches, each branch comprising a radio frequency tube, the source of the radio frequency tube in each branch being connected to a switch tube, the gate of each switch tube being connected to a controller; the source of the radio frequency tube in each branch is connected to the drain of the switch tube in the current branch, and the source of the switch tube is grounded; the gates of the radio frequency tubes in each branch are connected to each other, and the drains of the radio frequency tubes in each branch are connected to each other; the gates of the radio frequency tubes in the second gain amplification sub-modules a and b are connected to each other and then connected to the positive terminal of the secondary side of the first intermediate-stage transformer TR2, the gates of the radio frequency tubes in the second gain amplification sub-modules c and d are connected to each other and then connected to the negative terminal of the secondary side of the first intermediate-stage transformer TR2; the drains of the radio frequency tubes in the second gain amplification sub-modules a and c are connected to each other and then connected to the positive terminal of the primary side of a third intermediate-stage transformer TR3, and the drains of the radio frequency tubes in the second gain amplification sub-modules b and d are connected to each other and then connected to the negative terminal of the primary side of the third intermediate-stage transformer TR3, and the secondary side of the third intermediate-stage transformer TR3 serves as an output.