Low-loss radio frequency amplification circuit

Abstract

The invention discloses a low-loss radio frequency amplification circuit which comprises a power amplifier tube input matching circuit, a power amplifier tube, a power amplifier tube output matching circuit, a cascade microstrip line, a loop junction transmitting end input matching circuit, a loop junction, a loop junction receiving end output matching circuit and a loop junction common end matching circuit. The power amplifier tube input matching circuit matches the input impedance of the power amplifier chip to 50 ohms, and the power amplifier tube amplifies the input transmitting signal; the power amplifier tube output matching circuit, the cascade microstrip line and the loop junction transmitting end input matching circuit form a variable impedance circuit, the input impedance of the variable impedance circuit and the output impedance of the power amplifier tube are in a conjugate relationship, and the output impedance of the variable impedance circuit and the input impedance of the loop junction are in a conjugate relationship; and the ring junction receiving end output matching circuit and the ring junction common end matching circuit respectively match the input impedance of the ring junction receiving end and the input impedance of the ring junction common end to 50 ohms. The problem of large loss in the prior art can be solved.

Description

Technical Field

[0001] The invention belongs to the field of microwave technology, and in particular relates to a low-loss radio frequency amplifier circuit. Background Art

[0002] The amplifier circuit realizes the function of signal amplification in the radio frequency system. For a radio frequency amplification link with a common port for transmission and reception, the radio frequency signal is amplified by the power amplifier chip, and then transmitted to the transmitting output end by the circulator through the cascaded microstrip line. The existing design method of the radio frequency amplifier circuit is that the input and output port impedance of the power amplifier chip is designed to be 50 ohms, the characteristic impedance of the cascaded microstrip line is designed to be 50 ohms, and the input and output impedance of the circulator is designed to be 50 ohms, and then the three are cascaded to form a transmitting link. Because the power amplifier tube and the ring junction are both in a low-impedance state, the link has a low-impedance state that is transformed to 50 ohms through the output matching circuit of the power amplifier tube, and then after passing through the cascaded microstrip line, it is transformed to a low-impedance state through the input matching circuit of the transmitting end of the ring junction. There is a disadvantage that multiple impedance matching leads to large link loss. Summary of the invention

[0003] The purpose of the present invention is to provide a low-loss radio frequency amplifier circuit, which can solve the problem of high loss in the prior art.

[0004] One aspect of the present invention provides a low-loss radio frequency amplifier circuit, comprising a power amplifier chip, a cascaded microstrip line and a circulator, wherein the power amplifier chip comprises a power amplifier tube input matching circuit, a power amplifier tube and a power amplifier tube output matching circuit, and the circulator comprises a ring junction transmitting end input matching circuit, a ring junction, a ring junction receiving end output matching circuit and a ring junction common end matching circuit. The power amplifier tube input matching circuit is used to match the input impedance of the power amplifier chip to 50 ohms, and the power amplifier tube is used to amplify the input transmission signal; The power amplifier tube output matching circuit, the cascaded microstrip line, and the ring junction transmitter input matching circuit constitute a variable impedance circuit for impedance transformation. The input impedance of the variable impedance circuit is in a conjugate relationship with the output impedance of the power amplifier tube, and the output impedance of the variable impedance circuit is in a conjugate relationship with the input impedance of the ring junction. The ring junction is used to transmit the transmitting signal from the transmitting end to the common end output, and transmit the receiving signal from the common end to the receiving end output. The ring junction receiving end output matching circuit is used to match the ring junction receiving end input impedance to 50 ohms, and the ring junction common end matching circuit is used to match the ring junction common end input impedance to 50 ohms.

[0005] Preferably, the power amplifier tube input matching circuit, the ring junction receiving end output matching circuit, and the ring junction common end matching circuit use 50 ohms as the matching impedance value, and the output impedance of the power amplifier tube and the input impedance of the ring junction transmitting input end are both less than 50 ohms.

[0006] Preferably, the power amplifier tube input matching circuit includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a first resistor, a first microstrip line, and a second microstrip line, wherein one end of the first capacitor is connected to the input transmission signal, the other end is connected to one end of the second capacitor and one end of the first microstrip line, the other end of the second capacitor is connected to ground, the other end of the first microstrip line is connected to one end of the second microstrip line and one end of the third capacitor, the other end of the second microstrip line is connected to ground, the other end of the third capacitor is connected to one end of the first inductor and the input end of the power amplifier tube, the other end of the first inductor is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the fourth capacitor and the gate voltage power supply, and the other end of the fourth capacitor is connected to ground. Preferably, the power amplifier tube output matching circuit includes a third microstrip line to a fifth microstrip line, a fifth capacitor to a seventh capacitor, wherein one end of the third microstrip line is connected to the output end of the power amplifier tube, the other end of the third microstrip line is connected to one end of the fourth microstrip line and one end of the fifth microstrip line, the other end of the fourth microstrip line is connected to one end of the second inductor, the other end of the second inductor is connected to one end of the fifth capacitor and the leakage voltage power supply, the other end of the fifth capacitor is grounded, the other end of the fifth microstrip line is connected to one end of the seventh capacitor and the sixth capacitor, the other end of the seventh capacitor is connected to the ground, and the other end of the sixth capacitor is connected to the cascaded microstrip line. Preferably, the ring junction transmitting end input matching circuit, the ring junction receiving end output matching circuit and the ring junction common end matching circuit respectively include more than two sections of microstrip lines of different sizes.

[0007] Preferably, the input matching circuit of the transmitting end of the loop junction includes the sixth microstrip line and the seventh microstrip line, the output matching circuit of the receiving end of the loop junction includes the eighth microstrip line and the ninth microstrip line, and the common end matching circuit of the loop junction includes the tenth microstrip line and the eleventh microstrip line, wherein one end of the sixth microstrip line is connected to the cascade microstrip line, and the other end is connected to one end of the seventh microstrip line, the other end of the seventh microstrip line is connected to the transmitting input end of the loop junction, one end of the eighth microstrip line is connected to the receiving output end of the loop junction, and the other end is connected to one end of the ninth microstrip line, one end of the tenth microstrip line is connected to the common end of the loop junction, and the other end is connected to one end of the eleventh microstrip line, the receiving signal is input from the other end of the eleventh microstrip line and output from the other end of the ninth microstrip line, and the transmitting signal is output from the other end of the eleventh microstrip line.

[0008] The low-loss radio frequency amplifier circuit according to the above aspects of the present invention can solve the problem of high loss in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work: Figure 1 It is a principle block diagram of a low-loss radio frequency amplifier circuit according to an embodiment of the present invention; Figure 2 is a schematic diagram of a power amplifier tube input matching circuit according to an embodiment of the present invention; Figure 3 is a schematic diagram of a power amplifier tube output matching circuit according to an embodiment of the present invention; Figure 4 is a circuit diagram of a circulator according to an embodiment of the present invention; Figure 5 Schematic diagram of a variable impedance circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0011] The embodiments of the present invention provide a low-loss radio frequency amplifier circuit, such as Figure 1 As shown, the radio frequency amplifier circuit of the embodiment of the present invention includes a power amplifier chip A1, a cascaded microstrip line U3 and a circulator B1. The power amplifier chip A1 includes a power amplifier tube input matching circuit U1, a power amplifier tube P1 and a power amplifier tube output matching circuit U2. The circulator B1 includes a ring junction transmitting end input matching circuit U4, a ring junction U5, a ring junction receiving end output matching circuit U7 and a ring junction common end matching circuit U6.

[0012] The power amplifier input matching circuit U1 is used to match the input impedance of the power amplifier chip A1 to 50 ohms. The power amplifier tube P1 is used to amplify the input RF signal.

[0013] The power amplifier output matching circuit U2, the cascaded microstrip line U3, and the ring junction transmitter input matching circuit U4 constitute a variable impedance circuit for impedance transformation. The input impedance of the variable impedance circuit is conjugate with the output impedance of the power amplifier P1, and the output impedance of the variable impedance circuit is conjugate with the input impedance of the ring junction U5.

[0014] The ring junction U5 is used to transmit the transmission signal from the transmitting end to the common end output, and transmit the receiving signal from the common end to the receiving end output. The ring junction receiving end output matching circuit U7 is used to match the input impedance of the ring junction U5 receiving end to 50 ohms. The ring junction common end matching circuit is used to match the input impedance of the common end of the ring junction U5 to 50 ohms.

[0015] The input RF signal S1 (transmitting signal) is transmitted through the power amplifier tube input matching circuit U1 to the input end of the power amplifier tube P1. After the power amplifier tube P1 amplifies the input RF signal S1, it is output to the power amplifier tube output matching circuit U2, and then to the ring junction transmitting end input matching circuit U4 through the cascaded microstrip line U3, and then to the ring junction common end matching circuit U6 for output. The input RF signal S2 (receiving signal) is transmitted through the ring junction common end matching circuit U6 to the ring junction U5, and then to the ring junction receiving end output matching circuit U7 for output through the ring junction U5.

[0016] The power amplifier input matching circuit U1, the ring junction receiving end output matching circuit U7, and the ring junction common end matching circuit U6 use 50 ohms as the matching impedance value. The output impedance of the power amplifier tube P1 and the input impedance of the ring junction transmitting input end are both less than 50 ohms. The variable impedance circuit adjusts the input and output impedance values ​​of the variable impedance circuit by changing the width and length of the microstrip line.

[0017] First, the common end matching circuit U6 of the circulator B1 and the output matching circuit U7 of the circulator junction receiving end are matched to 50 ohms. At this time, the input impedance of the transmitting input end of the circulator junction is Zj, and the output impedance of the power amplifier tube P1 is Zs; secondly, the input impedance of the variable impedance circuit composed of the power amplifier tube output matching circuit U2, the cascaded microstrip line U3, and the circulator junction transmitting end input matching circuit U4 is matched to the conjugate of Zs, and the output impedance is matched to the conjugate of Zj; finally, the input impedance of the power amplifier tube input matching circuit U1 is matched to 50 ohms, and the output impedance is matched to the conjugate of the input impedance of the power amplifier tube P1.

[0018] The power amplifier input matching circuit U1 includes a microstrip line, a capacitor, a resistor and an inductor, and the number of each is not less than 1. Figure 2In the embodiment shown, the power amplifier input matching circuit U1 includes 4 capacitors (first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4), 1 inductor (first inductor L1), 2 microstrip lines (first microstrip line ML1, second microstrip line ML2), and a resistor (first resistor R1). Among them, one end of the first capacitor C1 is connected to the input transmission signal S1, the other end is connected to one end of the second capacitor C2 and one end of the first microstrip line ML1, the other end of the second capacitor C2 is connected to the ground, the other end of the first microstrip line ML1 is connected to one end of the second microstrip line ML2 and one end of the third capacitor C3, the other end of the second microstrip line ML2 is connected to the ground, the other end of the third capacitor C3 is connected to one end of the first inductor L1 and the input end of the power amplifier P1, the other end of the first inductor L1 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to one end of the fourth capacitor C4 and the gate voltage supply VG, and the other end of the fourth capacitor C4 is connected to the ground.

[0019] The power amplifier output matching circuit U2 includes a microstrip line, a capacitor and an inductor, and the number of each is not less than 1. Figure 3 and Figure 5 In the embodiment shown, the power amplifier output matching circuit includes three sections of microstrip lines (third microstrip line ML3 to fifth microstrip line ML5) and three capacitors (fifth capacitor C5, sixth capacitor C6 and seventh capacitor C7). Among them, one end of the third microstrip line ML3 is connected to the output end of the power amplifier tube P1, the other end of the third microstrip line ML3 is connected to one end of the fourth microstrip line ML4 and one end of the fifth microstrip line ML5, the other end of the fourth microstrip line ML4 is connected to one end of the second inductor L2, the other end of the second inductor L2 is connected to one end of the fifth capacitor C5 and the leakage voltage supply VD, the other end of the fifth capacitor C5 is grounded, the other end of the fifth microstrip line ML5 is connected to the seventh capacitor C7 and one end of the sixth capacitor C6, the other end of the seventh capacitor C7 is connected to the ground, and the other end of the sixth capacitor C6 is connected to the cascade microstrip line U3.

[0020] The ring junction transmitting end input matching circuit U4 includes 2 or more microstrip lines of different sizes; the ring junction receiving end output matching circuit U7 includes 2 or more microstrip lines of different sizes; the ring junction common end matching circuit U6 includes 2 or more microstrip lines of different sizes. Figure 4 and Figure 5 In the embodiment shown, the ring junction transmitting end input matching circuit U4 includes two sections of microstrip lines (the sixth microstrip line ML6 and the seventh microstrip line ML7); the ring junction receiving end output matching circuit U7 includes two sections of microstrip lines (the eighth microstrip line ML8 and the ninth microstrip line ML9), and the ring junction common end matching circuit U6 includes two sections of microstrip lines (the tenth microstrip line ML10 and the eleventh microstrip line ML11). Among them, One end of the sixth microstrip line ML6 is connected to the cascade microstrip line U3, and the other end is connected to one end of the seventh microstrip line ML7. The other end of the seventh microstrip line ML7 is connected to the transmitting input end of the loop junction U5. One end of the eighth microstrip line ML8 is connected to the receiving output end of the loop junction U5, and the other end is connected to one end of the ninth microstrip line ML9. The receiving signal is output from the other end of the ninth microstrip line ML9. One end of the tenth microstrip line ML10 is connected to the common end of the loop junction U5, and the other end is connected to one end of the eleventh microstrip line ML11. When the circuit is in the transmitting state, the transmitting signal is output from the other end of the eleventh microstrip line ML11. When the circuit is in the receiving state, the receiving signal is input from the other end of the eleventh microstrip line ML11.

[0021] In the embodiment of the present invention, the operating frequency band of all devices is 5-6 GHz.

[0022] According to the low-loss RF amplifier circuit of the embodiment of the present invention, the output matching circuit of the power amplifier tube, the cascaded microstrip line and the input matching circuit of the circulator transmitter are used as variable impedance circuits, and an integrated design is performed, so that the input impedance of the variable impedance circuit is a conjugate impedance with the output impedance of the power amplifier tube, and the output impedance is a conjugate with the input impedance of the transmitter of the ring junction, thereby reducing the loss caused by impedance transformation and having the characteristic of low insertion loss. The present invention matches the low resistance of the output end of the power amplifier tube with the low resistance of the transmitter input end of the ring junction through the cascaded microstrip line through the variable impedance circuit. Compared with the previous RF link in which the power amplifier output circuit is matched to 50 ohms, the transmitter input end of the ring junction is matched to 50 ohms, and the two are connected through the cascaded microstrip line, it has the characteristic of low loss.

[0023] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A low-loss radio frequency amplifier circuit, characterized in that: It includes a power amplifier chip, a cascaded microstrip line and a circulator, wherein the power amplifier chip includes a power amplifier tube input matching circuit, a power amplifier tube and a power amplifier tube output matching circuit, and the circulator includes a ring junction transmitting end input matching circuit, a ring junction, a ring junction receiving end output matching circuit and a ring junction common end matching circuit; The power amplifier tube input matching circuit is used to match the input impedance of the power amplifier chip to 50 ohms, and the power amplifier tube is used to amplify the input transmission signal; The power amplifier tube output matching circuit, the cascaded microstrip line, and the ring junction transmitter input matching circuit constitute a variable impedance circuit for impedance transformation. The input impedance of the variable impedance circuit is in a conjugate relationship with the output impedance of the power amplifier tube, and the output impedance of the variable impedance circuit is in a conjugate relationship with the input impedance of the ring junction. The ring junction is used to transmit the transmitting signal from the transmitting end to the common end output, and transmit the receiving signal from the common end to the receiving end output. The ring junction receiving end output matching circuit is used to match the ring junction receiving end input impedance to 50 ohms, and the ring junction common end matching circuit is used to match the ring junction common end input impedance to 50 ohms.

2. The radio frequency amplifier circuit according to claim 1, characterized in that: The power amplifier tube input matching circuit, the ring junction receiving end output matching circuit, and the ring junction common end matching circuit use 50 ohms as the matching impedance value, and the output impedance of the power amplifier tube and the input impedance of the ring junction transmitting input end are both less than 50 ohms.

3. The radio frequency amplifier circuit according to claim 1 or 2, characterized in that: The power amplifier tube input matching circuit includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first inductor, a first resistor, a first microstrip line, and a second microstrip line, wherein one end of the first capacitor is connected to the input transmission signal, and the other end is connected to one end of the second capacitor and one end of the first microstrip line, the other end of the second capacitor is connected to ground, the other end of the first microstrip line is connected to one end of the second microstrip line and one end of the third capacitor, the other end of the second microstrip line is connected to ground, the other end of the third capacitor is connected to one end of the first inductor and the input end of the power amplifier tube, the other end of the first inductor is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the fourth capacitor and the gate voltage power supply, and the other end of the fourth capacitor is connected to ground.

4. The radio frequency amplifier circuit according to claim 1 or 2, characterized in that: The power amplifier tube output matching circuit includes a third microstrip line to a fifth microstrip line, a fifth capacitor to a seventh capacitor, wherein one end of the third microstrip line is connected to the output end of the power amplifier tube, the other end of the third microstrip line is connected to one end of the fourth microstrip line and one end of the fifth microstrip line, the other end of the fourth microstrip line is connected to one end of the second inductor, the other end of the second inductor is connected to one end of the fifth capacitor and a leakage voltage power supply, the other end of the fifth capacitor is grounded, the other end of the fifth microstrip line is connected to one end of the seventh capacitor and the sixth capacitor, the other end of the seventh capacitor is connected to the ground, and the other end of the sixth capacitor is connected to the cascaded microstrip line.

5. The radio frequency amplifier circuit according to claim 1 or 2, characterized in that: The ring junction transmitting end input matching circuit, the ring junction receiving end output matching circuit and the ring junction common end matching circuit respectively include more than two sections of microstrip lines with different sizes.

6. The radio frequency amplification circuit according to claim 5, characterized in that: The input matching circuit of the transmitting end of the loop junction includes the sixth microstrip line and the seventh microstrip line, the output matching circuit of the receiving end of the loop junction includes the eighth microstrip line and the ninth microstrip line, and the common end matching circuit of the loop junction includes the tenth microstrip line and the eleventh microstrip line, wherein one end of the sixth microstrip line is connected to the cascade microstrip line, and the other end is connected to one end of the seventh microstrip line, the other end of the seventh microstrip line is connected to the transmitting input end of the loop junction, one end of the eighth microstrip line is connected to the receiving output end of the loop junction, and the other end is connected to one end of the ninth microstrip line, one end of the tenth microstrip line is connected to the common end of the loop junction, and the other end is connected to one end of the eleventh microstrip line, the receiving signal is input from the other end of the eleventh microstrip line, and output from the other end of the ninth microstrip line, and the transmitting signal is output from the other end of the eleventh microstrip line.

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