A millimeter wave low insertion loss high isolation radio frequency switch circuit

Abstract

The application discloses a millimeter wave low-insertion-loss high-isolation radio frequency switch circuit, which comprises a receiving branch circuit, a transmitting branch circuit and a gate bias voltage RG; the transmitting branch circuit is connected with an antenna end ANT of the transmitting branch through a transmission line TL1; the gate bias voltage RG is coupled with a GaN HEMT switch tube VGS1, the gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected with the antenna end ANT of the transmitting branch through the transmission line TL1 and a transmission line TL3; the receiving branch circuit is connected with an antenna end ANT of the receiving branch through a transmission line TL2; the gate bias voltage RG is coupled with a GaN HEMT switch tube VGS2, the gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, and the equivalent LC parallel circuit is connected with the antenna end ANT of the receiving branch through the transmission line TL2 and a transmission line TL4; and the application realizes the low-insertion-loss high-isolation effect of the radio frequency switch through the equivalent LC parallel circuit and the equivalent RC parallel circuit.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of radio frequency switches, in particular to a millimeter wave radio frequency switch circuit with low insertion loss and high isolation. BACKGROUND

[0002] As a key device for receiving and transmitting signals of a radio frequency front end, the radio frequency switch is an important component of the radio frequency front end circuit, and its performance directly affects the quality of the received and transmitted signals. Excellent insertion loss can not only improve the efficiency of the transmitter, but also improve the sensitivity of the receiver.

[0003] However, the traditional radio frequency switch structure uses a lambda / 4 transmission line to replace the series switch tube, but the transmission line cannot completely block the signal leakage in the millimeter wave frequency band. In order to improve the isolation, the general traditional series-parallel structure uses the method of iterating multiple parallel branches to improve the required isolation, resulting in large insertion loss, so improvement is needed.

[0004] Based on this, the application provides a millimeter wave radio frequency switch circuit with low insertion loss and high isolation to solve the above problems. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the application provides a millimeter wave radio frequency switch circuit with low insertion loss and high isolation to solve the problems of high insertion loss and high isolation of the traditional series-parallel switch in the prior art.

[0006] The application provides a millimeter wave radio frequency switch circuit with low insertion loss and high isolation. The following technical scheme is adopted:

[0007] A millimeter wave radio frequency switch circuit with low insertion loss and high isolation, comprising a receiving branch circuit, a transmitting branch circuit and a gate bias voltage RG;

[0008] The transmitting branch circuit is connected with an antenna end ANT of the transmitting branch through a transmission line TL1. One end of the gate bias voltage RG is coupled to a GaN HEMT switch tube VGS1, and the other end of the gate bias voltage RG is coupled to the gate of a second parallel branch GaN HEMT switch tube M1. The drain of the second parallel branch GaN HEMT switch tube M1 is connected with the antenna end ANT of the transmitting branch through the transmission line TL1. The source of the second parallel branch GaN HEMT switch tube M1 is grounded. The gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, and the equivalent LC parallel circuit is connected with the antenna end ANT of the transmitting branch through the transmission line TL1 and a transmission line TL3.

[0009] The receiving branch circuit is connected with the antenna end ANT of the receiving branch through a transmission line TL2; one end of the gate bias voltage RG is coupled to the GaN HEMT switch tube VGS2, and the other end of the gate bias voltage RG is coupled to the gate of the second parallel branch GaN HEMT switch tube M2; the drain of the second parallel branch GaN HEMT switch tube M2 is connected with the antenna end ANT of the receiving branch through a transmission line TL2; the source of the second parallel branch GaN HEMT switch tube M2 is grounded; and the gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, and the equivalent LC parallel circuit is connected with the antenna end ANT of the receiving branch through a transmission line TL2 and a transmission line TL4.

[0010] By adopting the above technical scheme, in the radio frequency switch circuit, the transmission lines are flexibly used on the transmitting branch and the receiving branch circuit to control the capacitance and inductance effect of the millimeter wave frequency band; meanwhile, under the transmission line with the inherent characteristic impedance Z0, by changing the size of the series transmission line, the gate bias voltage RG is coupled with the equivalent LC parallel circuit, so that the impedance is increased, thereby making the equivalent LC parallel circuit have high impedance to prevent signal leakage, further improving the insertion loss of the switch, and the equivalent LC parallel circuit is connected in parallel with the equivalent RC parallel circuit, further adjusting the biasing condition of the radio frequency switch circuit, ensuring that the GaN HEMT switch tube is at the best working point, thereby reducing the insertion loss of the radio frequency switch circuit, and realizing the radio frequency switch with low insertion loss and high isolation of the millimeter wave.

[0011] Optionally, the equivalent LC parallel circuit in the transmitting branch circuit comprises a resonant inductor TL5 and a second parallel branch GaN HEMT switch tube M3, the gate of the second parallel branch GaN HEMT switch tube M3 is coupled to the gate bias voltage RG, the resonant inductor TL5 is connected in series between the source and the drain of the second parallel branch GaN HEMT switch tube M3 to constitute the equivalent LC parallel circuit, the source of the second parallel branch GaN HEMT switch tube M3 is connected in parallel with the equivalent RC parallel circuit, and the drain of the second parallel branch GaN HEMT switch tube M3 is coupled to the transmitting end TX of the transmitting branch and the transmission line TL3, and the drain of the second parallel branch GaN HEMT switch tube M3 is connected with the antenna end ANT of the transmitting branch through the transmission line TL3 and the transmission line TL1;

[0012] The equivalent LC parallel circuit in the receiving branch circuit includes a resonant inductor TL6 and a second parallel branch GaN HEMT switch tube M4, a gate of the second parallel branch GaN HEMT switch tube M4 is coupled to a gate bias voltage RG, a resonant inductor TL6 is connected in series between a source and a drain of the second parallel branch GaN HEMT switch tube M4 to form the equivalent LC parallel circuit, the source of the second parallel branch GaN HEMT switch tube M4 is connected in parallel with an equivalent RC parallel circuit, the drain of the second parallel branch GaN HEMT switch tube M4 is coupled to a receiving end RX of the receiving branch and a transmission line TL4, and the drain of the second parallel branch GaN HEMT switch tube M4 is connected to an antenna end ANT of the receiving branch through the transmission line TL4 and a transmission line TL2.

[0013] By adopting the technical scheme, the resonant inductor TL5 and the resonant inductor TL6 are respectively connected in series between the source and the drain of the second parallel branch GaN HEMT switch tube M3 and the second parallel branch GaN HEMT switch tube M4 to form an LC resonant circuit, the equivalent LC circuit is composed of a resonant inductor and a resonant capacitor, the resonant frequency of the radio frequency switch circuit is determined, the maximum value of impedance is generated, the loss of the RF signal in the conversion process is reduced, thereby the insertion loss is reduced, meanwhile, the parallel branches between the transmitting branch and the receiving branch reduce mutual interference, the isolation of the radio frequency switch circuit is improved, and the reliable operation of the second parallel branch GaN HEMT switch tube under different temperatures and power supply voltages is ensured.

[0014] Optionally, the equivalent RC parallel circuit in the transmitting branch circuit includes an open transmission line TL7 and a resistor R1, the open transmission line TL7 is connected in series with the resistor R1 and then grounded to form the equivalent RC parallel circuit, and the source of the second parallel branch GaN HEMT switch tube M3 is respectively coupled to the open transmission line TL7 and the resistor R1.

[0015] The equivalent RC parallel circuit in the receiving branch circuit includes an open transmission line TL8 and a resistor R2, the open transmission line TL8 is connected in series with the resistor R2 and then grounded to form the equivalent RC parallel circuit, and the source of the second parallel branch GaN HEMT switch tube M4 is respectively coupled to the open transmission line TL8 and the resistor R8.

[0016] By adopting the above technical scheme, the source of the second parallel branch GaN HEMT switch tube M3 in the transmitting circuit is respectively coupled to the open circuit transmission line TL7 and the resistor R1, the open circuit transmission line TL7 plays a role of impedance transformation in the transmitting circuit, and the resistor R1 provides a bias of the transmitting circuit, thereby providing a stable bias voltage for the second parallel branch GaN HEMT switch tube M3, the source of the second parallel branch GaN HEMT switch tube M4 in the receiving circuit is respectively coupled to the open circuit transmission line TL8 and the resistor R2, the open circuit transmission line TL8 plays a role of impedance transformation in the receiving circuit, and the resistor R21 provides a bias of the receiving circuit, thereby providing a stable bias voltage for the second parallel branch GaN HEMT switch tube M3, and meanwhile, signal reflection and loss are reduced, and the isolation of the radio frequency circuit is further improved, and mutual interference is reduced.

[0017] Optionally, the transmitting branch circuit is connected in parallel with an off capacitor Coff3, the off capacitor Coff3 is connected in series with an inductor LTL5, the off capacitor Coff3 is connected in parallel with a capacitor CTL7 and a resistor R1 in turn and grounded, the resistor R1 is connected in series with the capacitor CTL7, an on capacitor Coff1 is connected in parallel between the output end of the transmission line TL3 and the output end of the transmission line TL1 and grounded, and the off capacitor Coff1 and the off capacitor Coff3 are equivalent off capacitors Coffx.

[0018] The receiving branch circuit is connected in parallel with an on resistor Ron4, the on resistor Ron4 is connected in series with an inductor LTL6, the on resistor Ron4 is connected in parallel with a capacitor CTL8 and a resistor R2 in turn and grounded, the resistor R2 is connected in series with the capacitor CTL8, and an on resistor Ron2 is connected in parallel between the output end of the transmission line TL4 and the output end of the transmission line TL2 and grounded.

[0019] By adopting the above technical scheme, when the TX transmitting end of the transmitting circuit is turned on, the second parallel branch GaN HEMT switch tube M1 and the second parallel branch GaN HEMT switch tube M3 on the parallel branch are in an off state, at this time, they are equivalent to the off capacitors Coffx, and the on resistor Ron4 and the on resistor Ron2 affect the size of the current, thereby adjusting the received RF signal; the transmission line is used to transmit high-frequency signals and has a characteristic impedance, and in matching with the transmitting and receiving circuits, the effective transmission of the RF signal is ensured, the insertion loss and reflection are reduced, and the isolation of the radio frequency circuit is improved.

[0020] Optionally, the inductor LTL5 in the transmitting branch circuit is connected in parallel with the off capacitor Coffx3 to form an LC parallel resonance, and the resonance frequency is

[0021] When the equivalent RC parallel circuit is added in the transmitting branch circuit, the impedance is recorded as: The capacitive reactance is:

[0022] By adopting the technical scheme, when L and C resonate at the center resonant frequency, the following is met: The LC parallel circuit (band-stop filter) formed by the parallel inductor LTL5 and the total Coff3 has high impedance to prevent signal leakage, further improving the insertion loss of the switch. At the same time, by adding the RC parallel circuit, the impedance is: The capacitive reactance is Compared with the original , It is equivalent to adding a part of capacitive reactance, thereby reducing the insertion loss of the RF switch circuit. When the transmit branch circuit is turned on, the RF signal is transmitted from the TX port to the ANT port. After the parallel switch tube adds the LC parallel circuit and the RC parallel circuit structure, point A will show high impedance to prevent the RF signal from leaking to the ground, thereby reducing the insertion loss of the TX branch.

[0023] Optionally, the impedance of the LC equivalent parallel circuit and the RC equivalent parallel circuit in series with the second parallel branch GaN HEMT switch tube M4 in the transmit branch circuit is: That is

[0024] By adopting the technical scheme, the impedance of the LC equivalent parallel circuit and the RC equivalent parallel circuit in series with the second parallel branch GaN HEMT switch tube M4 in the transmit branch circuit is: Where a represents the real part of the impedance, and b represents the imaginary part of the impedance. The on-resistance Ron4 of the switch tube is generally small, and 1+(ωR2C TL8 ) 2 is much larger than R2, so the real part a of the impedance can be approximately regarded as 0; similarly, 1+(ωR2C TL8 ) 2 is much larger than R2 2 ωC TL8 , so the imaginary part b of the real axis impedance can also be approximately regarded as 0, and the modulus of the impedance Z on can be approximately regarded as 0, and the second parallel branch forms a low impedance. At the same time, the RC parallel circuit also has a filtering effect. Therefore, as shown in Figure 4 , when the RX branch is turned off, the RF signal leaks from the ANT port / TX port to the RX port. After the parallel switch tube adds the LC parallel circuit and the RC parallel circuit structure, point B will show low impedance to make the leaked RF signal approximately shorted to the ground, thereby improving the isolation of the RX branch.

[0025] Optionally, one end of the receiving branch circuit is coupled to an antenna end ANT of the receiving branch circuit, and the other end of the receiving branch circuit is coupled to a receiving end RX of the receiving branch circuit.

[0026] By adopting the above technical solution, the RF signal is separated through the coupling of the antenna end ANT and the receiving end RX of the receiving branch circuit, preventing the RF signal from leaking from the antenna end ANT to the receiving end RX, and improving the isolation of the RF switch from the antenna end ANX to the receiving end RX.

[0027] Optionally, one end of the transmitting branch circuit is coupled to a transmitting end TX of the transmitting branch circuit, and the other end of the transmitting branch circuit is coupled to an antenna end ANT of the transmitting branch circuit.

[0028] By adopting the above technical solution, the RF signal is separated through the coupling of the antenna end ANT and the transmitting end TX of the transmitting branch circuit, and the RF signal is transmitted into the transmitting branch circuit through the transmitting end TX, and then transmitted to the antenna end ANT after being separated by the transmitting branch circuit, thereby improving the isolation of the RF switch from the transmitting end TX to the receiving end RX.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] 1. In the RF switch circuit, the transmission line is flexibly used on the transmitting branch and the receiving branch circuit to control the capacitance and inductance effect of the millimeter wave frequency band; meanwhile, under the inherent characteristic impedance Z0 of the transmission line, by changing the size of the series transmission line, the gate bias voltage RG is coupled to the equivalent LC parallel circuit, so that the impedance is increased, thereby making the equivalent LC parallel circuit have high impedance to prevent signal leakage, further improving the insertion loss of the switch, and the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, further adjusting the biasing condition of the RF switch circuit, ensuring that the GaN HEMT switch tube is at the best working point, thereby reducing the insertion loss of the RF switch circuit, and realizing a millimeter wave low-insertion-loss high-isolation RF switch;

[0031] 2. The resonant inductor TL5 and the resonant inductor TL6 are respectively connected in series between the source and the drain of the second parallel branch GaN HEMT switch tube M3 and the second parallel branch GaN HEMT switch tube M4 to form an LC resonant circuit, and the equivalent LC circuit is composed of a resonant inductor and a resonant capacitor, which determines the resonant frequency of the RF switch circuit, so as to make the impedance reach the maximum value, reduce the loss of the RF signal in the conversion process, thereby reducing the insertion loss, at the same time, the parallel branch between the transmitting branch and the receiving branch reduces the mutual interference, improves the isolation of the RF switch circuit, and ensures the reliable operation of the second parallel branch GaN HEMT switch tube at different temperatures and power supply voltages;

[0032] 3. The source of the second parallel branch GaN HEMT switch M3 in the transmitting circuit is respectively coupled to the open circuit transmission line TL7 and the resistor R1, the open circuit transmission line TL7 plays a role of impedance transformation in the transmitting circuit, and the resistor R1 provides a bias for the transmitting circuit, and provides a stable bias voltage for the second parallel branch GaN HEMT switch M3, the source of the second parallel branch GaN HEMT switch M4 in the receiving circuit is respectively coupled to the open circuit transmission line TL8 and the resistor R2, the open circuit transmission line TL8 plays a role of impedance transformation in the receiving circuit, and the resistor R21 provides a bias for the receiving circuit, and provides a stable bias voltage for the second parallel branch GaN HEMT switch M3, reduces signal reflection and loss, further improves the isolation of the radio frequency circuit, and reduces mutual interference;

[0033] 4. When the TX transmitting end of the transmitting circuit is turned on, the second parallel branch GaN HEMT switch M1 and the second parallel branch GaN HEMT switch M3 on the parallel branch are in an off state, at this time, the equivalent is an off capacitor Coffx; and the on resistance Ron4 and the on resistance Ron2 affect the size of the current, thereby adjusting the received RF signal; the transmission line is used to transmit high-frequency signals and has a characteristic impedance, which is matched with the transmitting and receiving circuits to ensure the effective transmission of the RF signal, reduce the insertion loss and reflection, and improve the isolation of the radio frequency circuit. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A millimeter wave low insertion loss and high isolation radio frequency switch circuit diagram is provided for the application.

[0035] Figure 2 An equivalent model diagram of the millimeter wave low insertion loss and high isolation radio frequency switch circuit is provided for the application.

[0036] Figure 3 A working principle diagram of the millimeter wave low insertion loss and high isolation radio frequency switch circuit is provided for the application.

[0037] Figure 4 A millimeter wave low insertion loss and high isolation radio frequency switch circuit in the application is provided. Figure 1 An insertion loss diagram of the millimeter wave low insertion loss and high isolation radio frequency switch circuit in the application is provided.

[0038] Figure 5 A non-adjacent same unit port isolation diagram of the millimeter wave low insertion loss and high isolation radio frequency switch circuit in the application is provided. Figure 1

[0039] A adjacent same unit port isolation diagram of the millimeter wave low insertion loss and high isolation radio frequency switch circuit in the application is provided. Figure 6 Figure 1

[0040] BRIEF DESCRIPTION OF DRAWINGS​​

[0041] 1, transmit branch circuit; 2, receive branch circuit; 3, antenna terminal ANT. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. Figures 1-2

[0043] The embodiments of the present application disclose a millimeter wave low insertion loss and high isolation radio frequency switch circuit. Referring to the accompanying drawings, the specific embodiments are described in detail below. Figure 1 ​The application discloses a millimeter wave low-insertion-loss high-isolation radio frequency switch circuit, which comprises a receiving branch circuit, a transmitting branch circuit and a gate bias voltage RG; TL1, TL2, TL3 and TL4 are all lambda / 4 wavelength transmission lines; the transmitting branch circuit is connected with an antenna end ANT of the transmitting branch circuit through the transmission line TL1; one end of the gate bias voltage RG is connected with a GaN HEMT switch tube VGS1, and the other end of the gate bias voltage RG is connected with a gate of a second parallel branch GaN HEMT switch tube M1; a drain of the second parallel branch GaN HEMT switch tube M1 is connected with the antenna end ANT of the transmitting branch circuit through the transmission line TL1; a source of the second parallel branch GaN HEMT switch tube M1 is grounded; the gate bias voltage RG is connected with a gate of a second parallel branch GaN HEMT switch tube M3; a resonant inductor TL5 is connected in series between a source and a drain of the second parallel branch GaN HEMT switch tube M3 to form an equivalent LC parallel circuit; the source of the second parallel branch GaN HEMT switch tube M3 is connected with an open circuit transmission line TL7 and a resistor R1 respectively; the open circuit transmission line TL7 is connected in series with the resistor R1 and then grounded to form an equivalent RC parallel circuit; a drain of the second parallel branch GaN HEMT switch tube M3 is connected with the antenna end ANT of the transmitting branch circuit through the transmission line TL1 and the transmission line TL3; the receiving branch circuit is connected with an antenna end ANT of the receiving branch circuit through the transmission line TL2; one end of the gate bias voltage RG is connected with a GaN HEMT switch tube VGS2, and the other end of the gate bias voltage RG is connected with a gate of a second parallel branch GaN HEMT switch tube M2; a drain of the second parallel branch GaN HEMT switch tube M2 is connected with the antenna end ANT of the receiving branch circuit through the transmission line TL2; a source of the second parallel branch GaN HEMT switch tube M2 is grounded; the gate bias voltage RG is connected with a gate of a second parallel branch GaN HEMT switch tube M4; a resonant inductor TL6 is connected in series between a source and a drain of the second parallel branch GaN HEMT switch tube M34 to form an equivalent LC parallel circuit; the source of the second parallel branch GaN HEMT switch tube M4 is connected with an open circuit transmission line TL8 and a resistor R2 respectively; the open circuit transmission line TL8 is connected in series with the resistor R2 and then grounded to form an equivalent RC parallel circuit; a drain of the second parallel branch GaN HEMT switch tube M4 is connected with the antenna end ANT of the receiving branch circuit through the transmission line TL2 and the transmission line TL4; one end of the receiving branch circuit is connected with an antenna end ANT of the receiving branch circuit, and the other end of the receiving branch circuit is connected with a receiving end RX of the receiving branch circuit; one end of the transmitting branch circuit is connected with a transmitting end TX of the transmitting branch circuit, and the other end of the transmitting branch circuit is connected with the antenna end ANT of the transmitting branch circuit; since the application works in a millimeter wave frequency band, the inductance and the capacitance are greatly affected by the inherent errors and the parasitic parameters; the TX / RX port in the application flexibly uses the transmission line to control the inevitable capacitance and inductance effects in the millimeter wave frequency band and to realize the effect of a wide band.For a transmission line with characteristic impedance Z0, by changing the size of the series transmission line, the required inductance value can be obtained, and the equivalent circuit impedance is X. L = jωL = Z0tan(βl); and for an open-circuit termination transmission line, for a given frequency f0, when the open-circuit transmission line length is less than a quarter wavelength, it presents a capacitance, which can be used as a capacitor, and the equivalent circuit impedance is

[0044] Referring to Figure 2 , the transmitting branch circuit is connected in parallel with the off-state capacitor Coff1, the off-state capacitor Coff1 is connected in parallel with the inductor LTL5, the off-state capacitor Coff1 is connected in series with the capacitor CTL7 and the resistor R1 respectively and grounded, the resistor R1 is connected in parallel with the capacitor CTL7, and the output end of the transmission line TL3 and the output end of the transmission line TL1 are connected in series with the off-state capacitor Coff1 and grounded; the off-state capacitor Coff1 and the off-state capacitor Coff3 are equivalent off-state capacitors Coffx; the receiving branch circuit is connected in parallel with the on-state resistor Ron4, the on-state resistor Ron4 is connected in parallel with the inductor LTL6, the on-state resistor Ron4 is connected in series with the capacitor CTL8 and the resistor R2 respectively and grounded, the resistor R2 is connected in parallel with the capacitor CTL8, and the output end of the transmission line TL4 and the output end of the transmission line TL2 are connected in series with the on-state resistor Ron2 and grounded.

[0045] Referring to Figure 3 In the equivalent model, the λ / 4 wavelength transmission line is a key component in the design of the RF switch. According to the on-state branch and the off-state branch of the switch, the λ / 4 wavelength transmission line will form a low impedance and a high impedance respectively to control the transmission of the RF signal. When the RF switch is on, according to the impedance formula of the capacitor In the millimeter wave frequency band, as the frequency increases, the impedance is constantly decreasing, and the parallel off-state switch tube forms a low-impedance path, causing signal leakage and deteriorating the insertion loss of the switch. If the RF switch is on, the parallel branch of the on-state branch at this time presents a high impedance, which can hinder the leakage of the RF signal to the ground and reduce the insertion loss; by adding a parallel inductor between the source and drain of the parallel switch tube, the equivalent Coff of the off-state switch tube at this time is resonated to solve the problem of low impedance of the parallel branch in the millimeter wave frequency band. The inductor LTL5 in the transmitting branch circuit is coupled with the equivalent off-state capacitor Coffx3 in the second parallel branch GaN HEMT switch tube M3 to form an LC parallel resonance, and the LC parallel resonance is: The LC parallel circuit (band-stop filter) formed by the parallel inductor LTL5 and the off-state capacitor Coff3 has a high impedance to prevent signal leakage, further improving the insertion loss of the switch. When the RC parallel circuit is added, the impedance at this time is: In the RC parallel circuit, the value of Rx is generally greater than 1000Ω, and the value of Cx is generally about one or two hundred fF. At this time, the capacitive reactance is Compared with the original , equivalent to increase a part of the capacitive reactance. When the transmitting branch circuit is turned on, the RF signal is transmitted from the TX port to the ANT port, and the second parallel branch GaN HEMT switch M3 increases the LC parallel circuit and the RC parallel circuit structure after point A will show high impedance to prevent RF signal leakage to the ground, reduce the insertion loss of the transmitting branch circuit. At the same time, according to the receiving branch circuit, the second parallel branch GaN HEMT switch M4 is in series with the LC equivalent parallel circuit and the RC equivalent parallel circuit, and the impedance of the second parallel branch GaN HEMT switch M4 is The formula can be transformed as Where A represents the real part of the impedance, and b represents the imaginary part of the impedance. The on-resistance Ron4 of the second parallel branch GaN HEMT switch M4 is generally small, and 1+(ωR2C TL8 ) 2 will be much larger than R2, so the real part A of the impedance can be approximately regarded as 0; similarly, 1+(ωR2C TL8 ) 2 will be much larger than R2 2 ωC TL8 , so the imaginary part b of the real axis impedance can also be approximately regarded as 0, and the modulus of the impedance Z on can be approximately regarded as 0. The second parallel branch forms a low impedance at the same time, and the RC parallel circuit also has a filtering effect. Therefore, as shown in Figure 4 , when the RX branch is turned off, the RF signal is transmitted from the ANT port / TX port to the RX port, and the parallel switch increases the LC parallel circuit and the RC parallel circuit structure after point B will show low impedance to make the leaked RF signal approximately shorted to the ground, improve the isolation of the RX branch.

[0046] Referring to Figure 4 , from the comparison of the insertion loss of the RF switch and the traditional series-parallel switch, it can be seen that the RF switch circuit reduces the insertion loss of the RF switch through the equivalent LC parallel circuit and the equivalent RC parallel circuit, and realizes the effect of low insertion loss of the RF switch.

[0047] Referring to Figure 5 and Figure 6From the comparison of the isolation of the radio frequency switch and the isolation of the traditional T / R switch, it can be seen that the radio frequency switch circuit has higher isolation than the traditional T / R switch at the non-adjacent same cell port and the adjacent same cell port through the equivalent LC parallel circuit and the equivalent RC parallel circuit, and the high isolation effect of the radio frequency switch is realized.

[0048] The working principle of the millimeter wave low insertion loss and high isolation radio frequency switch circuit in the embodiment of the present application is as follows: when the radio frequency switch is turned on, if the parallel branch of the transmitting branch circuit presents high impedance, the RF radio frequency signal can be hindered from leaking to the ground, and the insertion loss is reduced; an equivalent LC parallel circuit is added between the source-drain junction of the GaN HEMT switch tube M3 of the second parallel branch, at this time, the equivalent CoffX of the GaN HEMT switch tube M3 of the second parallel branch is turned off to resonate to solve the problem of low impedance of the parallel branch in the millimeter wave frequency band, the resonant inductor LTL5 is connected to the equivalent total Coff3 in the GaN HEMT switch tube M3 of the second parallel branch of the transmitting branch circuit, and the LC parallel resonance is formed. The LC parallel resonance satisfies The LC parallel circuit formed by the resonant inductor LTL5 and the total Coff3 has high impedance to prevent signal leakage, and further improves the insertion loss of the switch. When the equivalent RC parallel circuit is added, the impedance is recorded as: In the RC parallel circuit, the value of Rx is generally greater than 1000Ω, and the value of Cx is generally about a few hundred fF, at this time, the capacitive reactance is Compared with the original , It is equivalent to adding a part of capacitive reactance. Therefore, when the transmitting branch circuit is turned on, in the process of transmitting the RF radio frequency signal from the TXport to the ANT port, the point A after the second parallel branch GaN HEMT switch tube M3 adds the LC parallel circuit and the RC parallel circuit structure will show high impedance to prevent the radio frequency signal from leaking to the ground, and reduce the insertion loss of the transmitting branch circuit.

[0049] When the radio frequency switch is turned off, the parallel branch of the off branch presents low impedance, and the RF signal coupled from the antenna end ANT port or the transmitting branch to the receiving branch is shorted to the ground, and the isolation is improved; according to the receiving branch circuit, the impedance of the second parallel branch GaN HEMT switch tube M4 in series with the equivalent LC parallel circuit and the equivalent RC parallel circuit is The formula can be transformed into Wherein A represents the real part of the impedance, and b represents the imaginary part of the impedance. The on-resistance Ron4 of the second parallel branch GaN HEMT switch tube M4 is generally very small, and 1+(ωR2C TL8 ) 2It will be much larger than R2, so the real part A of the impedance can be approximated as 0; similarly, 1+(ωR2C) TL8 ) 2 It will be better than R2 2 ωC TL8 Much larger, so the imaginary part b of the real-axis impedance can also be approximated as 0, then the impedance Z on The modulus can be approximated as 0, and this second parallel branch forms a low impedance. When the receiving branch is turned off, during the process of the RF signal leaking from the ANTport / TX port to the RX port, the addition of an LC parallel circuit and an RC parallel circuit structure to the GaN HEMT switch M4 in the second parallel branch will result in a low impedance at point B, making the leaked RF signal approximately short-circuited to ground, thus improving the isolation of the receiving branch and achieving a millimeter-wave low insertion loss and high isolation RF switch.

[0050] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.

Claims

1. A millimeter wave low insertion loss high isolation radio frequency switch circuit, characterized by, Comprise: Receive branch circuit (2), transmit branch circuit (1) and gate bias voltage RG; The transmit branch circuit (1) is connected with the antenna end ANT (3) of the transmit branch through a transmission line TL1;One end of the gate bias voltage RG is coupled to the GaN HEMT switch tube VGS1, and the other end of the gate bias voltage RG is coupled to the gate of the second parallel branch GaN HEMT switch tube M1, the drain of the second parallel branch GaN HEMT switch tube M1 is connected with the antenna end ANT (3) of the transmit branch through a transmission line TL1;The source of the second parallel branch GaN HEMT switch tube M1 is grounded;The gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, and the equivalent LC parallel circuit is connected with the antenna end ANT (3) of the transmit branch through a transmission line TL1 and a transmission line TL3; The receive branch circuit (2) is connected with the antenna end ANT (3) of the receive branch through a transmission line TL2;One end of the gate bias voltage RG is coupled to the GaN HEMT switch tube VGS2, and the other end of the gate bias voltage RG is coupled to the gate of the second parallel branch GaN HEMT switch tube M2, the drain of the second parallel branch GaN HEMT switch tube M2 is connected with the antenna end ANT (3) of the receive branch through a transmission line TL2;The source of the second parallel branch GaN HEMT switch tube M2 is grounded;The gate bias voltage RG is coupled with an equivalent LC parallel circuit, the equivalent LC parallel circuit is connected in parallel with an equivalent RC parallel circuit, and the equivalent LC parallel circuit is connected with the antenna end ANT (3) of the receive branch through a transmission line TL2 and a transmission line TL4; The equivalent LC parallel circuit in the transmit branch circuit (1) comprises a resonant inductor TL5 and a second parallel branch GaN HEMT switch tube M3, the gate of the second parallel branch GaN HEMT switch tube M3 is coupled to the gate bias voltage RG, a resonant inductor TL5 is connected in series between the source and the drain of the second parallel branch GaN HEMT switch tube M3 to constitute the equivalent LC parallel circuit, the source of the second parallel branch GaN HEMT switch tube M3 is connected in parallel with the equivalent RC parallel circuit, and the drain of the second parallel branch GaN HEMT switch tube M3 is coupled to the transmission end TX of the transmit branch and the transmission line TL3, and the drain of the second parallel branch GaN HEMT switch tube M3 is connected with the antenna end ANT (3) of the transmit branch through a transmission line TL3 and a transmission line TL1; The equivalent LC parallel circuit in the receiving branch circuit (2) includes a resonant inductor TL6 and a second parallel branch GaN HEMT switch tube M4, the gate of the second parallel branch GaN HEMT switch tube M4 is coupled to a gate bias voltage RG, the source and the drain of the second parallel branch GaN HEMT switch tube M4 are connected in series with the resonant inductor TL6 to form the equivalent LC parallel circuit, the source of the second parallel branch GaN HEMT switch tube M4 is connected in parallel with an equivalent RC parallel circuit, the drain of the second parallel branch GaN HEMT switch tube M4 is coupled to a receiving end RX of the receiving branch and a transmission line TL4, and the drain of the second parallel branch GaN HEMT switch tube M4 is connected to an antenna end ANT (3) of the receiving branch through the transmission line TL4 and the transmission line TL2.

2. The millimeter wave low insertion loss and high isolation radio frequency switch circuit according to claim 1, wherein, The equivalent RC parallel circuit in the transmitting branch circuit (1) includes an open circuit transmission line TL7 and a resistor R1, the open circuit transmission line TL7 is connected in series with the resistor R1 and then grounded to form the equivalent RC parallel circuit; the source of the second parallel branch GaN HEMT switch tube M3 is coupled to the open circuit transmission line TL7 and the resistor R1, respectively; The equivalent RC parallel circuit in the receiving branch circuit (2) includes an open circuit transmission line TL8 and a resistor R2, the open circuit transmission line TL8 is connected in series with the resistor R2 and then grounded to form the equivalent RC parallel circuit; the source of the second parallel branch GaN HEMT switch tube M4 is coupled to the open circuit transmission line TL8 and the resistor R8, respectively.

3. The millimeter wave low insertion loss and high isolation radio frequency switch circuit according to claim 2, wherein, The transmitting branch circuit (1) is connected in parallel with an off-state capacitor Coff3, the off-state capacitor Coff3 is connected in parallel with an inductor LTL5, the off-state capacitor Coff3 is connected in series with a capacitor CTL7 and a resistor R1, respectively, and then grounded, the resistor R1 is connected in parallel with the capacitor CTL7, an off-state capacitor Coff1 is connected in series between the output end of the transmission line TL3 and the output end of the transmission line TL1, and then grounded, and the off-state capacitor Coff1 and the off-state capacitor Coff3 are equivalent off-state capacitors Coffx; The receiving branch circuit (2) is connected in parallel with an on-state resistor Ron4, the on-state resistor Ron4 is connected in parallel with an inductor LTL6, the on-state resistor Ron4 is connected in series with a capacitor CTL8 and a resistor R2, respectively, and then grounded, the resistor R2 is connected in parallel with the capacitor CTL8, and an on-state resistor Ron2 is connected in series between the output end of the transmission line TL4 and the output end of the transmission line TL2, and then grounded.

4. The millimeter wave low insertion loss and high isolation radio frequency switch circuit according to claim 3, wherein, The inductor LTL5 in the transmitting branch circuit (1) is connected in parallel with the off capacitor Coffx3 to form an LC parallel resonance, and the resonance frequency is When the equivalent RC parallel circuit is added in the transmitting branch circuit (1), the impedance is recorded as: The capacitive reactance is 5. The millimeter wave low insertion loss and high isolation radio frequency switch circuit according to claim 3, wherein, The impedance of the LC equivalent parallel circuit and the RC equivalent parallel circuit in series with the second parallel branch GaN HEMT switch tube M4 in the transmitting branch circuit (1) is: That is Wherein a represents the real part of the impedance, and b represents the imaginary part of the impedance.

6. The millimeter wave low insertion loss and high isolation radio frequency switch circuit according to claim 2, wherein, One end of the receiving branch circuit (2) is coupled to an antenna end ANT (3) of the receiving branch circuit (2), and the other end of the receiving branch circuit (2) is coupled to a receiving end RX of the receiving branch circuit (2).

7. The millimeter-wave low-insertion-loss high-isolation radio frequency switch circuit according to claim 2, wherein, One end of the transmitting branch circuit (1) is coupled to a transmitting end TX of the transmitting branch circuit (1), and the other end of the transmitting branch circuit (1) is coupled to an antenna end ANT (3) of the transmitting branch circuit (1).

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