Radio frequency front-end chip with power-off non-loss matching function

Abstract

The application discloses a radio frequency front-end chip with power-off non-loss matching function, which comprises a receiving path amplifier, a transmitting path amplifier, a receiving power-off non-loss matching circuit and a transmitting power-off non-loss matching circuit; the receiving power-off non-loss matching circuit is connected with the input end of the receiving path amplifier, and the receiving power-off non-loss matching circuit works when the receiving path amplifier does not work; the transmitting power-off non-loss matching circuit is connected with the input end of the transmitting path amplifier; and the transmitting power-off non-loss matching circuit works when the transmitting path amplifier does not work. The application can make the output end impedance of the transmitting path amplifier match the impedance of the 90-degree bridge of the front end when the transmitting path amplifier is closed, and can also make the input end impedance of the receiving path amplifier match the impedance of the 90-degree bridge of the front end when the receiving path amplifier is closed.

Description

Technical Field

[0001] This invention relates to the field of radio frequency communication, and in particular to a radio frequency front-end chip with a power-off matching function. Background Technology

[0002] Satellite internet technology has developed rapidly in recent years. In order to achieve low noise figure in reception and high power and efficiency in transmission, radio frequency front-end chips have become an indispensable part of the entire radio frequency link.

[0003] To overcome the polarization mismatch problem caused by the high-speed relative motion between low-orbit satellites and ground terminals, and to ensure the stability and reliability of communication links under complex propagation conditions, it is necessary to use circularly polarized antennas.

[0004] In traditional architectures, a 90-degree bridge circuit is connected to the rear end of a circularly polarized antenna. Behind this bridge, a single-pole double-throw switch connects to the transmitter amplifier (typically a power amplifier) ​​and receiver amplifier (typically a low-noise amplifier) ​​of the RF front-end chip. This architecture degrades both the receiver noise figure and the transmit power, with the former being particularly affected. Therefore, eliminating the single-pole double-throw switch would significantly improve the overall system noise figure. However, a major problem with conventional amplifiers is the severe mismatch between their input and output ports when off. Furthermore, the 90-degree bridge circuit required for circularly polarized antennas necessitates isolation port impedances close to 50 ohms to absorb any reflected power or energy leakage between ports and maintain the amplitude and phase balance of the output signal. This means that when the transmitting circuit is working (i.e., when the transmitting amplifier is working), the receiving amplifier is off, and the input impedance of the receiving amplifier must be close to 50 ohms; when the receiving circuit is working (i.e., when the receiving amplifier is working), the transmitting amplifier is off, and the output impedance of the transmitting amplifier must also be close to 50 ohms, which is contrary to the normal operating state of an amplifier.

[0005] In view of the above problems, it is necessary to study an RF front-end chip with power-off matching function, which can make the output impedance of the transmitter amplifier match the impedance of the 90-degree bridge of the front end when the transmitter amplifier is turned off, and can also make the input impedance of the receiver amplifier match the impedance of the 90-degree bridge of the front end when the receiver amplifier is turned off. Summary of the Invention

[0006] The purpose of this invention is to provide an RF front-end chip with a power-off impedance matching function, which enables the output impedance of the transmitting amplifier to match the impedance of the 90-degree bridge in the front-end when the transmitting amplifier is turned off, and also enables the input impedance of the receiving amplifier to match the impedance of the 90-degree bridge in the front-end when the receiving amplifier is turned off.

[0007] To achieve the above objectives, the solution of the present invention is:

[0008] A radio frequency front-end chip with power-off matching protection includes a receiver amplifier, a transmitter amplifier, a receiver power-off matching protection circuit, and a transmitter power-off matching protection circuit. The receiver power-off matching protection circuit is connected to the input terminal of the receiver amplifier and is used to adjust the impedance of the receiver amplifier's input terminal. The receiver power-off matching protection circuit is also connected to the control terminal of either the receiver amplifier or the transmitter amplifier, and is controlled by either the receiver amplifier or the transmitter amplifier. The transmitter power-off matching protection circuit is connected to the output terminal of the transmitter amplifier and is used to adjust the impedance of the transmitter amplifier's output terminal. The transmitter power-off matching protection circuit is also connected to the control terminal of either the receiver amplifier or the transmitter amplifier, and is controlled by either the receiver amplifier or the transmitter amplifier. When the receiver amplifier is working, the transmitter amplifier is not working, the transmitter power-off matching protection circuit is working, and the receiver power-off matching protection circuit is not working. Conversely, when the transmitter amplifier is working, the receiver amplifier is not working, the receiver power-off matching protection circuit is working, and the transmitter power-off matching protection circuit is not working.

[0009] The receiving circuit without loss of matching is controlled by the receiving amplifier. The receiving circuit without loss of matching includes resistors R11 and R12, capacitors C11 and C12, and a switching transistor SW11. The first terminal of capacitor C11 is connected to the input terminal of the receiving amplifier, and the second terminal of capacitor C11 is connected to the drain of the switching transistor SW1. The first terminal of resistor R11 is connected to the gate of the switching transistor SW1, and the second terminal of resistor R11 is grounded. The first terminal of resistor R12 is connected to the source of the switching transistor SW1, and the second terminal of resistor R12 is connected to the control terminal of the receiving amplifier. When the receiving amplifier is working, the control terminal of the receiving amplifier is at a high level; when the receiving amplifier is not working, the control terminal of the receiving amplifier is at a low level.

[0010] The transmit-power-off-match-free circuit is controlled by the transmit amplifier. The transmit-power-off-match-free circuit includes resistors R21, R22, and R23; capacitors C21 and C22; and switching transistors SW21 and SW22. The first terminal of capacitor C21 is connected to the output terminal of the transmit amplifier, and the second terminal of capacitor C21 is connected to the drain of switching transistor SW21. The first terminal of resistor R21 is connected to the gate of switching transistor SW21, and the second terminal of resistor R21 is grounded. The first terminal of resistor R22 is connected to the gate of switching transistor SW22, and the second terminal of resistor R22 is grounded. The first terminal of resistor R23 is connected to the source of switching transistor SW22, and the second terminal of resistor R23 is connected to the control terminal of the transmit amplifier. The source of switching transistor SW21 is connected to the drain of switching transistor SW22. When the transmit amplifier is working, the control terminal of the transmit amplifier is at a high level; when the transmit amplifier is not working, the control terminal of the transmit amplifier is at a low level.

[0011] The receive-without-power-loss-matching circuit is controlled by the transmit amplifier. The receive-without-power-loss-matching circuit includes resistors R11' and R12', capacitors C11' and C12', and a switching transistor SW11'. The first terminal of capacitor C11' is connected to the input terminal of the receive amplifier, and the second terminal of capacitor C11' is connected to the drain of the switching transistor SW11'. The first terminal of capacitor C12' is connected to the source of the switching transistor SW11', and the second terminal of capacitor C12' is grounded. The first terminal of resistor R11' is connected to the gate of the switching transistor SW11', and the second terminal of resistor R11' is connected to the control terminal of the transmit amplifier. The first terminal of resistor R12' is connected to the source of the switching transistor SW11', and the second terminal of resistor R12' is connected to the power supply VCC. When the transmit amplifier is working, the control terminal of the transmit amplifier is at a high level; when the transmit amplifier is not working, the control terminal of the transmit amplifier is at a low level.

[0012] The transmit-without-matching-loss circuit is controlled by the receive amplifier; the transmit-without-matching-loss circuit includes resistors R21', R22', R23', capacitors C21' and C22', and switching transistors SW21' and SW22'; the first terminal of capacitor C21' is connected to the output terminal of the transmit amplifier, the second terminal of capacitor C21' is connected to the drain of switching transistor SW21', the first terminal of capacitor C22' is connected to the source of switching transistor SW21', the second terminal of capacitor C22' is directly grounded, and the first terminal of resistor R21' is connected to the source of switching transistor SW21'. The gate of transistor SW21' is connected to the control terminal of the receiving amplifier via the second end of resistor R21' and the first end of resistor R22'. The second end of resistor R22' is connected to the gate of switching transistor SW22'. The first end of resistor R23' is connected to the source of switching transistor SW22', and the second end of resistor R23' is connected to the power supply VCC. The source and drain of switching transistor SW21' and switching transistor SW22' are connected. When the receiving amplifier is working, the control terminal of the receiving amplifier is in a high-level state. When the receiving amplifier is not working, the control terminal of the receiving amplifier is in a low-level state.

[0013] The receiver amplifier, transmitter amplifier, receiver power-off matching circuit, and transmitter power-off matching circuit are integrated into the RF front-end chip with power-off matching function using GaAs pHEMT, SiGe BiCMOS, or SOI CMOS technology.

[0014] The receiving amplifier is a low-noise amplifier, and the transmitting amplifier is a power amplifier.

[0015] After adopting the above scheme, the working principle of the present invention is as follows:

[0016] When the RF front-end chip is in receive mode, the receiver amplifier is active while the transmitter amplifier is inactive. At this time, the receiver power-off matching circuit does not operate and does not affect the operation of the receiver amplifier. The input impedance of the receiver amplifier exhibits its inherent 50-ohm input impedance matching state. Simultaneously, the transmitter power-off matching circuit operates and adjusts the output impedance of the transmitter amplifier to 50 ohms, ensuring that the output impedance of the transmitter amplifier and the input impedance of the receiver amplifier are both impedance-matched with both ends of the 90-degree bridge in the front-end. This guarantees the balance of the 90-degree bridge, minimizes its insertion loss, and thus improves the noise performance of the receiving system, including the 90-degree bridge.

[0017] When the RF front-end chip is in transmit mode, the transmit amplifier is active while the receive amplifier is inactive. At this time, the transmit-to-disconnect-matching circuit does not operate and does not affect the operation of the transmit amplifier. The output impedance of the transmit amplifier exhibits its inherent 50-ohm output impedance matching state. Simultaneously, the receive-to-disconnect-matching circuit operates and adjusts the input impedance of the receive amplifier to 50 ohms, ensuring that the input impedance of the receive amplifier and the output impedance of the transmit amplifier are impedance matched with both ends of the 90-degree bridge at the front end. This guarantees the balance of the 90-degree bridge, minimizing insertion loss and thus improving the power performance of the transmit system, including the 90-degree bridge.

[0018] As can be seen from the above, the present invention enables the output impedance of the transmitting amplifier to match the impedance of the 90-degree bridge at the front end when the transmitting amplifier is turned off, and also enables the input impedance of the receiving amplifier to match the impedance of the 90-degree bridge at the front end when the receiving amplifier is turned off, thus ensuring the stability and reliability of the entire RF link. Attached Figure Description

[0019] Figure 1 This is a circuit schematic diagram of Embodiment 1 of the present invention.

[0020] Figure 2 This is a schematic diagram of the input standing wave characteristics of the RF front-end chip in transmit mode after removing the power-off matching circuit of Embodiment 1.

[0021] Figure 3 This is a schematic diagram of the input standing wave characteristics of the radio frequency front-end chip in transmit mode according to Embodiment 1 of the present invention.

[0022] Figure 4 This is a schematic diagram of the noise characteristics of the RF front-end chip in receive mode after removing the power-off matching circuit of Embodiment 1.

[0023] Figure 5 This is a schematic diagram of the noise characteristics of the radio frequency front-end chip in receiving mode according to Embodiment 1 of the present invention.

[0024] Figure 6 This is a circuit schematic diagram of Embodiment 2 of the present invention. Detailed Implementation

[0025] like Figure 1 and Figure 6As shown, this invention discloses a radio frequency front-end chip with power-off matching protection, comprising a receiver amplifier, a transmitter amplifier, a receiver power-off matching protection circuit, and a transmitter power-off matching protection circuit. The receiver amplifier can be a low-noise amplifier, and the transmitter amplifier can be a power amplifier. The receiver power-off matching protection circuit is connected to the input terminal of the receiver amplifier and is used to adjust the impedance of the receiver amplifier's input terminal. The receiver power-off matching protection circuit is connected to the control terminal of either the receiver amplifier or the transmitter amplifier, and is controlled by either the receiver amplifier or the transmitter amplifier. The transmitter-without-matching circuit is connected to the output of the transmitter amplifier. It is used to adjust the impedance of the transmitter amplifier's output. It is also connected to the control terminal of either the receiver amplifier or the transmitter amplifier, and is controlled by either the receiver amplifier or the transmitter amplifier. When the receiver amplifier is working, the transmitter amplifier is not working; the transmitter-without-matching circuit is working, but the receiver-without-matching circuit is not working. Conversely, when the transmitter amplifier is working, the receiver amplifier is not working; the receiver-without-matching circuit is working, but the transmitter-without-matching circuit is not working.

[0026] The working principle of this invention is as follows:

[0027] When the RF front-end chip is in receive mode, the receiver amplifier is active while the transmitter amplifier is inactive. At this time, the receiver power-off matching circuit does not operate and does not affect the operation of the receiver amplifier. The input impedance of the receiver amplifier exhibits its inherent 50-ohm input impedance matching state. Simultaneously, the transmitter power-off matching circuit operates and adjusts the output impedance of the transmitter amplifier to 50 ohms, ensuring that the output impedance of the transmitter amplifier and the input impedance of the receiver amplifier are both impedance-matched with both ends of the 90-degree bridge in the front-end. This guarantees the balance of the 90-degree bridge, minimizes its insertion loss, and thus improves the noise performance of the receiving system, including the 90-degree bridge.

[0028] When the RF front-end chip is in transmit mode, the transmit amplifier is active while the receive amplifier is inactive. At this time, the transmit-to-disconnect-matching circuit does not operate and does not affect the operation of the transmit amplifier. The output impedance of the transmit amplifier exhibits its inherent 50-ohm output impedance matching state. Simultaneously, the receive-to-disconnect-matching circuit operates and adjusts the input impedance of the receive amplifier to 50 ohms, ensuring that the input impedance of the receive amplifier and the output impedance of the transmit amplifier are impedance matched with both ends of the 90-degree bridge at the front end. This guarantees the balance of the 90-degree bridge, minimizing insertion loss and thus improving the power performance of the transmit system, including the 90-degree bridge.

[0029] As described above, this invention enables the output impedance of the transmitting amplifier to match the impedance of the 90-degree bridge at the front end when the transmitting amplifier is turned off, and also enables the input impedance of the receiving amplifier to match the impedance of the 90-degree bridge at the front end when the receiving amplifier is turned off, ensuring the stability and reliability of the entire RF link. The receiving amplifier, transmitting amplifier, receiving power-off matching-free circuit, and transmitting power-off matching-free circuit can be integrated into this RF front-end chip with power-off matching-free functionality using GaAs pHEMT, SiGe BiCMOS, or SOI CMOS processes.

[0030] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0031] Example 1:

[0032] Cooperate Figure 1As shown, in Embodiment 1 of the present invention, the receiving power-off non-matching circuit is controlled by the receiving amplifier; the receiving power-off non-matching circuit may include resistors R11 and R12, capacitors C11 and C12, and a switching transistor SW11; the first end of capacitor C11 is connected to the input terminal of the receiving amplifier, the second end of capacitor C11 is connected to the drain of the switching transistor SW1, the first end of resistor R11 is connected to the gate of the switching transistor SW1, the second end of resistor R11 is grounded, the first end of resistor R12 is connected to the source of the switching transistor SW1, and the second end of resistor R12 is connected to the control terminal of the receiving amplifier; when the receiving amplifier is working, When the control terminal of the receiver amplifier is high, the switch SW1 is off, causing the receiver power-off mismatch circuit to be inactive (the receiver power-off mismatch circuit is in a high-impedance state). The receiver power-off mismatch circuit has minimal impact on the noise of the receiver amplifier. When the receiver amplifier is not working, its control terminal is low, and the switch SW1 is on, causing the receiver power-off mismatch circuit to be active. The receiver power-off mismatch circuit controls the input impedance of the receiver amplifier to be 50 ohms within the receiving frequency band, providing a relatively ideal load condition for the 90-degree bridge at the front end and ensuring the balance of the bridge. Among them, capacitor C11 mainly serves to isolate DC and provide RF matching, while capacitor C12 mainly serves to isolate DC and provide RF ground. Resistors R11 and R12 can effectively isolate DC and RF paths to suppress noise, leakage, and parasitic coupling at the control terminal of the receiver amplifier.

[0033] Cooperate Figure 1As shown, in Embodiment 1 of the present invention, the transmit-power-off-match-free circuit is controlled by the transmit amplifier; the transmit-power-off-match-free circuit includes resistors R21, R22, and R23, capacitors C21 and C22, and switching transistors SW21 and SW22; the first end of capacitor C21 is connected to the output terminal of the transmit amplifier, and the second end of capacitor C21 is connected to the drain of switching transistor SW21; the first end of resistor R21 is connected to the gate of switching transistor SW21, and the second end of resistor R21 is grounded; the first end of resistor R22 is connected to the gate of switching transistor SW22, and the second end of resistor R22 is grounded; the first end of resistor R23 is connected to the source of switching transistor SW22, and the second end of resistor R23 is connected to the control terminal of the transmit amplifier; the source of switching transistor SW21 is connected to... The drain connection of switch SW22 is as follows: When the transmitter amplifier is working, its control terminal is high, turning off both switches SW21 and SW22. The transmit power-off mismatch circuit is inactive (high impedance state), and its impact on the receiver amplifier's output power is minimal. When the transmitter amplifier is not working, its control terminal is low, turning on both switches SW21 and SW22. The transmit power-off mismatch circuit is active, controlling the transmitter amplifier's output impedance to be 50 ohms within the transmission frequency band, providing a relatively ideal load condition for the 90-degree bridge at the front end and ensuring bridge balance. Capacitor C21 primarily isolates DC and provides RF matching, while capacitor C22 primarily isolates DC and provides RF ground. Resistors R21, R22, and R23 effectively isolate DC and RF paths to suppress noise, leakage, and parasitic coupling at the transmitter amplifier's control terminal.

[0034] To facilitate understanding of this invention, the following tests are conducted on the noise characteristics of the RF front-end chip in receive mode and the input standing wave characteristics in transmit mode.

[0035] Figure 3 This is a schematic diagram illustrating the input standing wave characteristics of the RF front-end chip in transmit mode according to Embodiment 1 of the present invention. It can be seen that within the transmit frequency range of 10.5GHz-12.75GHz, the input standing wave of the receiver is generally less than -20dB, and the impedance is 50 ohms. For comparison, Figure 2 The diagram shows the input standing wave characteristics of the RF front-end chip in transmit mode after removing the power-off matching circuit of Embodiment 1. The input standing wave of the receiver is greater than -2dB, and the impedance mismatch is very serious.

[0036] Figure 5This is a schematic diagram illustrating the noise characteristics of the RF front-end chip in receiving mode according to Embodiment 1 of the present invention. It can be seen that within the receiving frequency range of 10.5GHz-12.75GHz, the noise of the receiving path is less than 1.05dB. For comparison, Figure 4 This is a schematic diagram showing the noise characteristics of the RF front-end chip in receive mode after removing the power-off matching circuit of Embodiment 1. Figure 4 and Figure 5 The comparison shows that the noise degradation after adding the receiver power-off mismatch circuit is very small, about 0.05dB.

[0037] Example 2:

[0038] Cooperate Figure 6 As shown, in Embodiment 2 of the present invention, the receive-without-power-loss-matching circuit is controlled by the transmit amplifier; the receive-without-power-loss-matching circuit may include resistors R11' and R12', capacitors C11' and C12', and a switching transistor SW11'; the first end of capacitor C11' is connected to the input terminal of the receive amplifier, the second end of capacitor C11' is connected to the drain of the switching transistor SW11', the first end of capacitor C12' is connected to the source of the switching transistor SW11', and the second end of capacitor C12' is grounded; the first end of resistor R11' is connected to the gate of the switching transistor SW11', and the second end of resistor R11' is connected to the control terminal of the transmit amplifier; the first end of resistor R12' is connected to the source of the switching transistor SW11', and the second end of resistor R12' is connected to the source of the switching transistor SW11'. The second terminal is connected to the power supply VCC. When the receiving amplifier is working, the transmitting amplifier is not working, causing its control terminal to be at a low level, which turns off the switching transistor SW11'. At this time, the receiving power-off mismatch circuit is in a non-working state (presenting a high impedance state), and has little impact on the noise of the receiving circuit. When the receiving amplifier is not working, the transmitting amplifier is working, causing its control terminal to be at a high level, which turns on the switching transistor SW11'. At this time, the receiving power-off mismatch circuit works, controlling the input impedance of the receiving amplifier to be close to 50 ohms in the receiving frequency band (e.g., 10.5-12.75GHz), providing a relatively ideal load condition for the front-end 90-degree bridge. Among them, capacitor C11' mainly plays the role of DC isolation and RF matching, capacitor C12' mainly plays the role of DC isolation and providing RF ground, and resistors R11' and R12' can effectively isolate DC and RF paths, suppress control terminal noise, leakage and parasitic coupling.

[0039] Cooperate Figure 6As shown, in Embodiment 2 of the present invention, the transmit-without-power-loss-matching circuit is controlled by the receive amplifier; the transmit-without-power-loss-matching circuit may include resistors R21', R22', R23', capacitors C21', C22', and switching transistors SW21' and SW22'; the first end of capacitor C21' is connected to the output terminal of the transmit amplifier, the second end of capacitor C21' is connected to the drain of switching transistor SW21', the first end of capacitor C22' is connected to the source of switching transistor SW21', and the second end of capacitor C22' is directly grounded; the first end of resistor R21' is connected to the gate of switching transistor SW21', the second end of resistor R21' is connected to the control terminal of the receive amplifier after being connected to the first end of resistor R22', and the second end of resistor R22' is connected to the gate of switching transistor SW22'; the first end of resistor R23' is connected to the source of switching transistor SW22', and the second end of resistor R23' is connected to the drain of the receive amplifier. The source of switch SW21' and the drain of switch SW22' are connected to VCC. When the transmitter amplifier is working, the receiver amplifier is not working, causing its control terminal to be at a low level, thus turning off switches SW21' and SW22'. At this time, the transmit power-off mismatch circuit is inactive (exhibiting a high impedance state), having minimal impact on the transmitter amplifier's output power. The stacked structure of switches SW21' and SW22' also helps to withstand higher output power. When the transmitter amplifier is not working, the receiver amplifier is working, causing its control terminal to be at a high level, turning on switches SW21' and SW22'. At this time, the transmit power-off mismatch circuit is active, controlling the transmitter amplifier's output impedance to be close to 50 ohms within the transmission frequency band, providing relatively ideal load conditions for the front-end 90-degree bridge. Capacitor C21' mainly serves to isolate DC and provide RF matching, while capacitor C22' mainly serves to isolate DC and provide RF ground. Resistors R21', R22', and R23' can effectively isolate the DC and RF paths, suppress control noise, leakage, and parasitic coupling.

[0040] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A radio frequency front-end chip with power-off match retention function, characterized in that: This includes a receiver amplifier, a transmitter amplifier, a receiver power-off matching circuit, and a transmitter power-off matching circuit. The receiver without loss of matching circuit is connected to the input terminal of the receiver amplifier. The receiver without loss of matching circuit is used to adjust the impedance of the input terminal of the receiver amplifier. The receiver without loss of matching circuit is controlled by the receiver amplifier. The power-off matching-free receiving circuit includes resistors R11 and R12, capacitors C11 and C12, and a switching transistor SW11. The first terminal of capacitor C11 is connected to the input of the receiving amplifier, and the second terminal of capacitor C11 is connected to the drain of the switching transistor SW1. The first terminal of resistor R11 is connected to the gate of the switching transistor SW1, and the second terminal of resistor R11 is grounded. The first terminal of resistor R12 is connected to the source of the switching transistor SW1, and the second terminal of resistor R12 is connected to the control terminal of the receiving amplifier. When the receiving amplifier is working, the control terminal of the receiving amplifier is at a high level; when the receiving amplifier is not working, the control terminal of the receiving amplifier is at a low level. The transmit-power-off-match-free circuit is connected to the output of the transmit amplifier. The transmit-power-off-match-free circuit is used to adjust the impedance of the output of the transmit amplifier. The transmit-power-off-match-free circuit is controlled by the transmit amplifier. The transmit-without-matching circuit includes resistors R21, R22, and R23, capacitors C21 and C22, and switching transistors SW21 and SW22. The first terminal of capacitor C21 is connected to the output of the transmit amplifier, and the second terminal is connected to the drain of switching transistor SW21. The first terminal of resistor R21 is connected to the gate of switching transistor SW21, and the second terminal is grounded. The first terminal of resistor R22 is connected to the gate of switching transistor SW22, and the second terminal is grounded. The first terminal of resistor R23 is connected to the source of switching transistor SW22, and the second terminal is connected to the control terminal of the transmit amplifier. The source of switching transistor SW21 is connected to the drain of switching transistor SW22. When the transmit amplifier is working, its control terminal is at a high level; when the transmit amplifier is not working, its control terminal is at a low level. When the receiving amplifier is working, the transmitting amplifier is not working; the power-off matching circuit for transmitting is working, while the power-off matching circuit for receiving is not working.

2. The RF front-end chip with power-off match retention function as described in claim 1, characterized in that: The receiver amplifier, transmitter amplifier, receiver power-off matching circuit, and transmitter power-off matching circuit are integrated into the RF front-end chip with power-off matching function using GaAspHEMT, SiGe BiCMOS, or SOI CMOS technology.

3. The RF front-end chip with power-off match retention function as described in claim 1, characterized in that: The receiving amplifier is a low-noise amplifier, and the transmitting amplifier is a power amplifier.

4. A radio frequency front-end chip with power-off match retention function, characterized in that: This includes a receiver amplifier, a transmitter amplifier, a receiver power-off matching circuit, and a transmitter power-off matching circuit. The receiver impedance matching circuit is connected to the input of the receiver amplifier and is used to adjust the impedance at the input of the receiver amplifier. The receiver impedance matching circuit is controlled by the transmitter amplifier. The receiver impedance matching circuit includes resistors R11' and R12', capacitors C11' and C12', and a switching transistor SW11'. The first terminal of capacitor C11' is connected to the input of the receiver amplifier, and the second terminal of capacitor C11' is connected to the drain of the switching transistor SW11'. The first terminal of capacitor C12' is connected to the source of the switching transistor SW11', and the second terminal of capacitor C12' is grounded. The first terminal of resistor R11' is connected to the gate of the switching transistor SW11', and the second terminal of resistor R11' is connected to the control terminal of the transmitter amplifier. The first terminal of resistor R12' is connected to the source of the switching transistor SW11', and the second terminal of resistor R12' is connected to the power supply VCC. When the transmitter amplifier is working, the control terminal of the transmitter amplifier is at a high level; when the transmitter amplifier is not working, the control terminal of the transmitter amplifier is at a low level. The transmit-power-off-match-free circuit is connected to the output of the transmit amplifier. It is used to adjust the impedance of the transmit amplifier's output and is controlled by the receive amplifier. The transmit-without-matching circuit includes resistors R21', R22', R23', capacitors C21' and C22', and switching transistors SW21' and SW22'. The first terminal of capacitor C21' is connected to the output of the transmit amplifier, and the second terminal is connected to the drain of switching transistor SW21'. The first terminal of capacitor C22' is connected to the source of switching transistor SW11', and the second terminal is directly grounded. The first terminal of resistor R21' is connected to the gate of switching transistor SW21'. The second end of resistor R21 is connected to the first end of resistor R22, which in turn connects to the control terminal of the receiving amplifier. The second end of resistor R22 is connected to the gate of switching transistor SW22. The first end of resistor R23 is connected to the source of switching transistor SW22, and the second end of resistor R23 is connected to the power supply VCC. The source of switching transistor SW21 and the drain of switching transistor SW22 are connected. When the receiving amplifier is working, the control terminal of the receiving amplifier is in a high-level state; when the receiving amplifier is not working, the control terminal of the receiving amplifier is in a low-level state. When the receiving amplifier is working, the transmitting amplifier is not working; the power-off matching circuit for transmitting is working, while the power-off matching circuit for receiving is not working.

5. The RF front-end chip with power-off match retention function as described in claim 4, characterized in that: The receiver amplifier, transmitter amplifier, receiver power-off matching circuit, and transmitter power-off matching circuit are integrated into the RF front-end chip with power-off matching function using GaAspHEMT, SiGe BiCMOS, or SOI CMOS technology.

6. The RF front-end chip with power-off match retention function as described in claim 4, characterized in that: The receiving amplifier is a low-noise amplifier, and the transmitting amplifier is a power amplifier.

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