High-power frequency modulation transmitter power amplifier

Abstract

According to the power amplifier of the high-power frequency modulation transmitter, an input impedance network adopts two stages of coaxial Balun impedance, the first stage converts input impedance into balanced 25 ohms, and the second stage converts impedance into 6.25 ohms. The output impedance network is also provided with two stages of Balun impedances, the first stage converts the input impedance into balanced 25 ohms, and the second stage converts the impedance into unbalanced 50 ohms. According to the utility model, through the continuous multi-stage impedance conversion network, the consistency of frequency response of the matching network in a broadband can be ensured, the consistency of gains of different frequency points in a wider frequency spectrum range can be ensured, and the gain fluctuation in the whole band can be reduced. Through rapid impedance conversion, simplification of a matching network, reduction of components participating in matching and reduction of loss, the output power of a power amplification chip is transmitted to the rearmost end as much as possible, and the maximum peak power and the corresponding working efficiency of the power amplifier are effectively guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of wireless communication and broadcasting, in particular to a high-power frequency modulation transmitter power amplifier. Background Art

[0002] In current wireless communication and broadcasting systems, high-power FM transmitters play a vital role. As its core component, the power amplifier plays a vital role in the performance of the transmitter, and its performance directly determines the transmission effect and coverage of the entire system. However, traditional power amplifier designs often have problems such as low efficiency and poor linearity, which to a certain extent limits the performance improvement of FM transmitters. Therefore, developing a new type of power amplifier to improve its performance and efficiency has become an urgent need in the current industry. Utility Model Content

[0003] The utility model provides a high-power FM transmitter power amplifier, which is based on a new matching method and aims to solve the problems existing in the prior art. The new matching method achieves high-efficiency, high-linearity high-power output by optimizing circuit design.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] The utility model discloses a high-power FM transmitter power amplifier, comprising an input matching network, an output matching network and a power amplification unit. The input matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the input impedance from an unbalanced 50 ohms to a balanced 25 ohms through a 50 ohm coaxial semi-steel cable. The second stage converts the impedance to 6.25 ohms through a 25 ohm coaxial semi-steel cable. The specific circuit structure of the input matching network is as follows:

[0006] The first-stage input matching network is a coaxial balun impedance, specifically a 50-ohm coaxial semi-steel cable; wherein the input signal is connected to the inner conductor of the input end of the 50-ohm coaxial semi-steel cable, and the outer conductor of the input end of the 50-ohm coaxial semi-steel cable is grounded;

[0007] The second-stage input matching network is a coaxial balun impedance, using two 25-ohm coaxial semi-steel cables A and B; wherein, the inner conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of A, and the outer conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of B; the inner conductors of A and B are connected together and connected to one end of R8, the other end of R8 is connected to the active end of R2, one end of R2 is connected to one end of R1, the other end of R1 is connected to the output end of U1, C4 is connected between the connecting line between R1 and U1 and the ground; the other end of R2 is connected to Q1, R3 is connected between the c pole of Q1 and R2, R5 is connected between the b pole of Q1 and R2, R6 is connected between the b pole and the e pole of Q1, and the e pole is grounded;

[0008] The inner conductor of the A output terminal is connected to the outer conductor of the B output terminal and then connected to one control terminal of U2; the outer conductor of the A output terminal is connected to the inner conductor of the B output terminal and then connected to another control terminal of U2;

[0009] Q1 is a transistor, U1 is a low voltage dropout linear regulator; U2 is an LDMOS chip, and U2 and its peripheral circuits together constitute a power amplifier unit.

[0010] The output matching network adopts two-stage coaxial balun impedance conversion. The first stage converts the output impedance from 6.25 ohms to 25 ohms through a 12.5 ohm coaxial semi-steel cable; the second stage converts the impedance from balanced 25 ohms to unbalanced 50 ohms through a 50 ohm coaxial semi-steel cable. The specific circuit structure of the output matching network is as follows:

[0011] The output matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the two 6.25 ohm balanced signals output by the power amplifier unit into two 25 ohm balanced signals through two 12.5 ohm coaxial semi-steel cables. The second stage converts the two 25 ohm balanced signals into unbalanced 50 ohm RF signals after passing through 50 ohm coaxial semi-steel cables. The two 12.5 ohm coaxial semi-steel cables are marked as C and D respectively. The specific circuit structure is as follows:

[0012] One output signal of the power amplifier unit is connected to the outer conductor of the C input terminal and the inner conductor of the D input terminal; another output signal of the power amplifier unit is connected to the inner conductor of the C input terminal and the outer conductor of the D input terminal; the outer conductors of the output terminals of C and D are respectively connected to filter capacitors and then grounded; the inner conductor of the output terminal of C is connected to the outer conductor of the input terminal of a 50-ohm coaxial semi-steel cable, the inner conductor of the output terminal of D is connected to the inner conductor of the input terminal of the 50-ohm coaxial semi-steel cable, the outer conductor of the output terminal of the 50-ohm coaxial semi-steel cable is grounded, and the inner conductor of the output terminal of the 50-ohm coaxial semi-steel cable serves as the power amplifier output terminal of the FM transmitter.

[0013] The U1 is specifically BL9198-33BAPRN.

[0014] The U2 is specifically HTH8G02P1K4H.

[0015] The Q1 is specifically BC847.

[0016] A signal processing method for a high-power frequency modulation transmitter is provided. An input matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the input impedance from unbalanced 50 ohms to balanced 25 ohms through a 50-ohm coaxial semi-steel cable, and the second stage converts the impedance to 6.25 ohms through a 25-ohm coaxial semi-steel cable. An output matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the output impedance from 6.25 ohms to 25 ohms through a 12.5-ohm coaxial semi-steel cable, and the second stage converts the impedance from balanced 25 ohms to unbalanced 50 ohms through a 50-ohm coaxial semi-steel cable.

[0017] In the input matching network, after the input signal is input to the inner conductor of the input end of the 50-ohm coaxial semi-steel cable, it is output from the inner conductor and outer conductor of the output end of the 50-ohm coaxial semi-steel cable; the inner conductor of the output end of the 50-ohm coaxial semi-steel cable is connected to the inner conductor of the A input end and the outer conductor of the B input end, and the outer conductor of the output end of the 50-ohm coaxial semi-steel cable is respectively connected to the outer conductor of the A input end and the inner conductor of the B input end; the outer conductor of the output end of A is connected to the inner conductor of the output end of B, and the outer conductor of the output end of B is connected to the inner conductor of the output end of A, and the inner conductor of the output end of A is connected to the control end of one of the power amplifier units as a control signal; the inner conductor of the output end of B is connected to the control end of another power amplifier unit;

[0018] A and B are 25 ohm coaxial semi-steel cables.

[0019] In the output matching network, the first-stage output impedance adopts two 12.5-ohm coaxial semi-steel cables C and D, wherein the inner conductor of the C input end is connected to the output of one of the power amplifier units, the outer conductor of the D input end is connected to the output of the other power amplifier unit, the outer conductor of the C input end is connected to the inner conductor of the D input end, and the outer conductor of the D input end is connected to the inner conductor of the C input end;

[0020] The inner conductor of the output end of C is connected to the outer conductor of the output end of D, and the outer conductor of the output end of C is connected to the inner conductor of the output end of D. The inner conductor of the output end of C and the inner conductor of the output end of D are used as two balanced signals and input to the second stage of the output matching network. The second stage of the output matching network adopts a 50-ohm coaxial semi-steel cable. The inner conductor and outer conductor of the input end of the 50-ohm coaxial semi-steel cable are respectively connected to the inner conductor of the output end of C and the inner conductor of the output end of D or the inner conductor of the output end of D and the inner conductor of the output end of C; the inner conductor of the output end of the 50-ohm coaxial semi-steel cable is connected as the output signal of the high-power FM transmitter, and the outer conductor of the output end of the 50-ohm coaxial semi-steel cable is grounded. The impedance conversion is converted from balanced 25 ohms to unbalanced 50 ohms through the 50-ohm coaxial semi-steel cable.

[0021] The beneficial effects obtained by the utility model are:

[0022] High efficiency: Reduce power loss and improve power conversion efficiency by optimizing matching network design.

[0023] High linearity: Select high-performance power amplifier components to ensure that the power amplifier maintains good linearity at high power output and reduces signal distortion.

[0024] Good stability: Through temperature compensation and frequency tuning circuits, the impact of temperature changes and frequency drift on the performance of the power amplifier is reduced to maintain its stable operation.

[0025] Easy to implement and control costs: The power amplifier of the utility model adopts conventional circuit elements and mature process technology, which is easy to implement and control costs.

[0026] This solution uses domestically produced components to achieve high-end substitution in this field. The prepared power amplifier has the advantages of high efficiency, high linearity, wide bandwidth and good thermal stability. These advantages enable the application of this power amplifier in FM transmitters to significantly improve its performance and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit structure schematic diagram of the input impedance network of the utility model.

[0028] Figure 2 It is a circuit structure schematic diagram of the output impedance network of the utility model.

[0029] Figure 3 It is a complete circuit structure schematic diagram of the utility model. DETAILED DESCRIPTION

[0030] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0031] The utility model of high-power FM transmitter power amplifier is mainly composed of input matching network, power amplifier unit, output matching network, temperature compensation and frequency tuning circuit and control unit. The temperature compensation and frequency tuning circuit and control unit adopt conventional design. The power amplifier unit is mainly composed of HTH8G02P1K4H chip with peripheral circuit.

[0032] Among them, the input matching network adopts a new matching method, which is composed of multiple impedance converters and resonant circuits. Through reasonable impedance transformation and phase adjustment, it is used to achieve the best matching between the input signal and the power amplifier unit, thereby improving the power transmission efficiency.

[0033] The input impedance network uses a two-stage coaxial balun impedance conversion. The first stage inputs the unbalanced 50-ohm RF signal from the left end and converts it into two 25-ohm balanced signals through a 50-ohm coaxial semi-steel cable. The second stage converts the two 25-ohm balanced signals into two 6.25-ohm balanced signals through a 25-ohm coaxial semi-steel cable. The specific circuit structure is as follows: Figure 1 shown.

[0034] The input signal is connected to the inner conductor of the input end of the 50-ohm coaxial semi-steel cable, and the outer conductor of the input end of the 50-ohm coaxial semi-steel cable is grounded. The second-stage input matching network is a coaxial balun impedance, using two 25-ohm coaxial semi-steel cables A and B. The connection between the first stage and the second stage is as follows: the inner conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of the input end of A, and the outer conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of the input end of B; the inner conductors of A and B are connected together and connected to one end of R8, the other end of R8 is connected to the active end of R2, one end of R2 is connected to one end of R1, the other end of R1 is connected to the output end of U1, and C4 is connected between the connecting line between R1 and U1 and the ground; the other end of R2 is connected to Q1, R3 is connected between the c pole of Q1 and R2, R5 is connected between the b pole of Q1 and R2, R6 is connected between the b pole and the e pole of Q1, and the e pole is grounded.

[0035] The inner conductor of the A output terminal is connected to the outer conductor of the B output terminal and then connected to one control terminal of U2; the outer conductor of the A output terminal is connected to the inner conductor of the B output terminal and then connected to another control terminal of U2;

[0036] Q1 is a triode, the specific model is BC847. U1 is a low voltage drop linear regulator, the specific model is BL9198-33BAPRN; U2 is an LDMOS chip, the specific model is HTH8G02P1K4H, U2 and its peripheral circuits together form a power amplifier unit. R2 is a variable resistor.

[0037] This multi-stage continuous impedance transformation network can ensure the consistency of the frequency response of the matching network within a broadband, can ensure the consistency of gain at different frequency points within a wider spectrum range, and reduce gain fluctuations within the entire band.

[0038] Output matching network: This network also uses a new matching method to ensure the best match between the output power of the power amplifier unit and the load, further improving the power conversion efficiency.

[0039] The output impedance network uses a two-stage coaxial balun impedance conversion. The first stage converts the input impedance from 6.25 ohms to balanced 25 ohms through a 12.5 ohm coaxial semi-steel cable; the second stage converts the impedance from balanced 25 ohms to unbalanced 50 ohms through a 50 ohm coaxial semi-steel cable. The specific connections are as follows:

[0040] The first stage inputs two 6.25 ohm balanced signals, which are converted into two 25 ohm balanced signals after passing through 12.5 ohm coaxial semi-steel cables. The second stage converts two 25 ohm balanced signals into unbalanced 50 ohm RF signals after passing through 50 ohm coaxial semi-steel cables.

[0041] One output signal of the power amplifier unit is connected to the outer conductor of the C input terminal and the inner conductor of the D input terminal; another output signal of the power amplifier unit is connected to the inner conductor of the C input terminal and the outer conductor of the D input terminal; the outer conductors of the output terminals of C and D are respectively connected to filter capacitors and then grounded; the inner conductor of the output terminal of C is connected to the outer conductor of the input terminal of a 50-ohm coaxial semi-steel cable, the inner conductor of the output terminal of D is connected to the inner conductor of the input terminal of the 50-ohm coaxial semi-steel cable, the outer conductor of the output terminal of the 50-ohm coaxial semi-steel cable is grounded, and the inner conductor of the output terminal of the 50-ohm coaxial semi-steel cable serves as the power amplifier output terminal of the FM transmitter.

[0042] This continuous multi-stage impedance conversion network simplifies the matching network through fast impedance conversion, reduces the components involved in matching, reduces losses, and transmits the output power of the power amplifier chip to the end as much as possible, effectively ensuring the maximum peak power and corresponding working efficiency of the power amplifier. The specific circuit of the output matching network is as follows Figure 2 shown.

[0043] The power amplifier unit uses a domestically produced LDMOS power amplifier chip with wide bandwidth and high linearity: HTH8G02P1K4H. This domestically produced amplifier chip has a high power density, with a single-tube saturation power of up to 1400 watts and a saturation efficiency of 70%. Both the single-tube power and saturation efficiency are firsts in China, and the internally integrated enhanced ESD design and the industry's latest heat dissipation design process enhance robustness while achieving excellent thermal stability, achieving high efficiency, high linearity and high power output.

[0044] Temperature compensation and frequency tuning circuit: This circuit is used to monitor the temperature changes and frequency drifts of the power amplifier, and maintain the stable operation of the power amplifier through corresponding compensation and tuning measures.

[0045] The control unit is responsible for monitoring the working status of the power amplifier and adjusting its working parameters as needed to ensure its stable and efficient operation.

[0046] By adopting a new matching method and a high-performance power amplifier device, the high-power FM transmitter power amplifier of the utility model has the advantages of high efficiency, high linearity, wide bandwidth, good thermal stability, etc. These advantages enable the application of the power amplifier in the FM transmitter to significantly improve its performance and efficiency. At the same time, the utility model also has the advantages of simple structure, easy implementation, low cost, etc., and has the value of wide promotion.

Claims

1. A high-power FM transmitter power amplifier, comprising an input matching network, an output matching network and a power amplification unit, characterized in that: The input matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the input impedance from unbalanced 50 ohms to balanced 25 ohms through a 50 ohm coaxial semi-steel cable, and the second stage converts the impedance to 6.25 ohms through a 25 ohm coaxial semi-steel cable. The specific circuit structure of the input matching network is as follows: The first-stage input matching network is a coaxial balun impedance, specifically a 50-ohm coaxial semi-steel cable; wherein the input signal is connected to the inner conductor of the input end of the 50-ohm coaxial semi-steel cable, and the outer conductor of the input end of the 50-ohm coaxial semi-steel cable is grounded; The second-stage input matching network is a coaxial balun impedance, using two 25-ohm coaxial semi-steel cables A and B; wherein, the inner conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of A, and the outer conductor of the output end of the 50-ohm coaxial semi-steel cable of the first-stage input matching network is connected to the outer conductor of B; the inner conductors of the input ends of A and B are connected together and connected to one end of R8, the other end of R8 is connected to the active end of R2, one end of R2 is connected to one end of R1, the other end of R1 is connected to the output end of U1, C4 is connected between the connecting line between R1 and U1 and the ground; the other end of R2 is connected to Q1, R3 is connected between the c pole of Q1 and R2, R5 is connected between the b pole of Q1 and R2, R6 is connected between the b pole and the e pole of Q1, and the e pole is grounded; The inner conductor of the A output terminal is connected to the outer conductor of the B output terminal and then connected to one control terminal of U2; the outer conductor of the A output terminal is connected to the inner conductor of the B output terminal and then connected to another control terminal of U2; Q1 is a transistor, U1 is a low voltage dropout linear regulator; U2 is an LDMOS chip, and U2 and its peripheral circuits together constitute a power amplifier unit.

2. The high-power FM transmitter power amplifier according to claim 1, characterized in that: The output matching network adopts two-stage coaxial balun impedance conversion. The first stage converts the output impedance from 6.25 ohms to 25 ohms through a 12.5 ohm coaxial semi-steel cable; the second stage converts the impedance from balanced 25 ohms to unbalanced 50 ohms through a 50 ohm coaxial semi-steel cable. The specific circuit structure of the output matching network is as follows: The output matching network adopts a two-stage coaxial balun impedance conversion. The first stage converts the two 6.25 ohm balanced signals output by the power amplifier unit into two 25 ohm balanced signals through two 12.5 ohm coaxial semi-steel cables. The second stage converts the two 25 ohm balanced signals into unbalanced 50 ohm RF signals after passing through 50 ohm coaxial semi-steel cables. The two 12.5 ohm coaxial semi-steel cables are marked as C and D respectively. The specific circuit structure is as follows: One output signal of the power amplifier unit is connected to the outer conductor of the C input terminal and the inner conductor of the D input terminal; another output signal of the power amplifier unit is connected to the inner conductor of the C input terminal and the outer conductor of the D input terminal; the outer conductors of the output terminals of C and D are connected to filter capacitors and then grounded; The inner conductor of the C output end is connected to the outer conductor of the 50-ohm coaxial semi-steel cable input end, the inner conductor of the D output end is connected to the inner conductor of the 50-ohm coaxial semi-steel cable input end, the outer conductor of the 50-ohm coaxial semi-steel cable output end is grounded, and the inner conductor of the 50-ohm coaxial semi-steel cable output end serves as the power amplifier output end of the FM transmitter.

3. The high-power FM transmitter power amplifier according to claim 1, characterized in that: The U1 is specifically BL9198-33BAPRN.

4. The high-power FM transmitter power amplifier according to claim 1, characterized in that: The U2 is specifically HTH8G02P1K4H.

5. The high-power FM transmitter power amplifier according to claim 1, characterized in that: The Q1 is specifically BC847.

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