Amplitude limiting circuit and communication equipment

Abstract

The utility model discloses an amplitude limiting circuit and communication equipment, and the amplitude limiting circuit comprises an amplitude limiting module, a voltage control attenuation module and a voltage control module. The amplitude limiting module is used for reducing the signal amplitude of the received input radio frequency signal, outputting a first radio frequency signal and outputting a coupling signal according to the first radio frequency signal; the voltage-controlled attenuation module is connected with the amplitude limiting module; the voltage-controlled attenuation module is used for reducing the signal amplitude of the first radio frequency signal to be not greater than a target threshold value according to a target attenuation value and then outputting a second radio frequency signal; the voltage control module is respectively connected with the amplitude limiting module and the voltage control attenuation module; the voltage control module is used for outputting a voltage control voltage according to the size of the detection coupling signal and a preset threshold voltage so as to adjust the attenuation value of the voltage control attenuation module to a target attenuation value. According to the invention, the application requirement of the radio frequency agility device can be met, and the problem that the receiving sensitivity of the whole device is reduced due to system noise brought to the receiving link by the pi-type attenuator can be relieved.

Description

Technical Field

[0001] The present application relates to the field of radio frequency technology, and in particular to a limiting circuit and communication equipment. Background Art

[0002] In order to prevent the RF agile chip from inputting too large a signal and causing excessive power loss in the integrated chip, a limiting circuit is usually added to the input end of the integrated chip for protection.

[0003] The limiting threshold of the ordinary limiting circuit cannot meet the maximum input power requirement of the RF agile chip, which forces a sufficiently large π-type attenuator to be used in the limiting circuit to limit the maximum input power to the RF agile chip. The added π-type attenuator will increase the system noise of the receiving link and reduce the receiving sensitivity of the device.

[0004] Therefore, the current technology still needs to be improved and enhanced. Utility Model Content

[0005] The present application provides a limiting circuit and a communication device, wherein the limiting circuit can meet the application requirements of a radio frequency agile device, and at the same time can alleviate the problem of reducing the receiving sensitivity of the entire device due to the system noise brought by a π-type attenuator to a receiving link.

[0006] The present application provides a limiting circuit, the limiting circuit comprising:

[0007] A limiting module, the limiting module is used to reduce the signal amplitude of the received input radio frequency signal and then output a first radio frequency signal, and output a coupled signal according to the first radio frequency signal;

[0008] A voltage-controlled attenuation module, the voltage-controlled attenuation module is connected to the amplitude limiting module; the voltage-controlled attenuation module is used to reduce the signal amplitude of the first radio frequency signal to no greater than the target threshold value according to the target attenuation value and then output a second radio frequency signal;

[0009] The voltage control module is connected to the limiting module and the voltage-controlled attenuation module respectively; the voltage control module is used to output a voltage-controlled voltage according to the size of the coupling signal and a preset threshold voltage to adjust the attenuation value of the voltage-controlled attenuation module to a target attenuation value.

[0010] In some embodiments, the limiting circuit, the voltage control module includes:

[0011] A detection unit, the detection unit is connected to the limiting module, and the detection unit is used to output a detection level according to the coupled signal;

[0012] The voltage control unit is connected to the detection unit and is used to output a voltage-controlled voltage according to the size of the detection level and a preset threshold voltage to adjust the attenuation value of the voltage-controlled attenuation module to a target attenuation value.

[0013] In some embodiments, the limiting circuit, the limiting module includes:

[0014] A limiting unit, the limiting unit is used to reduce the signal amplitude of the received input radio frequency signal and then output a first radio frequency signal;

[0015] The coupling unit is connected to the limiting unit, and is used to output the first radio frequency signal to the voltage-controlled attenuation module, and output a coupled signal to the detection unit according to the first radio frequency signal.

[0016] In the limiting circuit of some embodiments, the detection unit includes a detection tube, the input end of the detection tube is connected to the coupling unit, and the output end of the detection tube is connected to the voltage control unit.

[0017] In some embodiments of the limiting circuit, the voltage control unit includes a first operational amplifier and a second operational amplifier, the inverting input terminal of the first operational amplifier is connected to the voltage output terminal of the detection tube, the non-inverting input terminal of the first operational amplifier is used to receive a preset threshold voltage, the output terminal of the first operational amplifier is connected to the voltage-controlled attenuation module and the inverting input terminal of the first operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the detection tube, the inverting input terminal of the second operational amplifier is grounded, and the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier and the voltage-controlled attenuation module.

[0018] In some embodiments of the limiting circuit, the coupling unit includes a coupler, a first resistor, a second resistor, a third resistor and a fourth resistor, the input end of the coupler is connected to the limiting unit, the coupling end of the coupler is connected to one end of the first resistor and one end of the fourth resistor, the other end of the first resistor and one end of the second resistor are grounded, the other end of the second resistor is connected to the other end of the fourth resistor, and the other end of the fourth resistor is connected to the detection unit; the output end of the coupler is connected to the voltage-controlled attenuation module, and the isolation end of the coupler is grounded through the third resistor.

[0019] In some embodiments of the limiting circuit, the limiting unit includes a limiting tube and a first inductor, the input end of the limiting tube is used to access the input RF signal, the output end of the limiting tube is connected to the coupling unit, one end of the first inductor is connected to the output end of the limiting tube, and the other end of the first inductor is grounded.

[0020] In some embodiments, the amplitude limiting circuit, the voltage-controlled attenuation module includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a first diode, a second diode, a third diode, a fourth diode, a fifth resistor and a sixth resistor;

[0021] One end of the first capacitor is connected to the coupling unit, the other end of the first capacitor is connected to the anode of the third diode through the second capacitor, the anode of the first diode and one end of the third inductor are connected to the other end of the first capacitor, the cathode of the first diode is grounded through the fifth resistor, the other end of the third inductor is connected to the output end of the second operational amplifier, one end of the fifth capacitor is connected to the other end of the third inductor, and the other end of the fifth capacitor is grounded; one end of the fourth inductor is connected to the anode of the third diode, the other end of the fourth inductor is connected to the output end of the first operational amplifier, one end of the seventh capacitor is connected to the other end of the fourth inductor, and the other end of the seventh capacitor is grounded; the cathode of the third diode is connected to the cathode of the fourth diode and one end of the second inductor The first operational amplifier is connected to the first inductor, the other end of the second inductor is grounded, the anode of the fourth diode is connected to one end of the fifth inductor and one end of the third capacitor, the other end of the third capacitor is connected to one end of the fourth capacitor, the other end of the fourth capacitor is used to output a second RF signal, the anode of the second diode is connected to one end of the fourth capacitor, the cathode of the second diode is grounded through the sixth resistor, one end of the fifth inductor is connected to the other end of the third capacitor, the other end of the fifth inductor is connected to one end of the eighth capacitor and the output end of the first operational amplifier, the other end of the eighth capacitor is grounded, one end of the sixth inductor is connected to one end of the fourth capacitor, the other end of the sixth inductor is connected to one end of the sixth capacitor and the output end of the second operational amplifier, and the other end of the sixth capacitor is grounded.

[0022] In some embodiments of the amplitude limiting circuit, the voltage control unit further includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor and a sixteenth resistor;

[0023] One end of the eighth resistor is connected to the voltage-controlled attenuation module, the other end of the eighth resistor is connected to the output end of the first operational amplifier, one end of the ninth resistor is used to access the preset threshold voltage, the other end of the ninth resistor is connected to one end of the seventh resistor and the non-inverting input end of the first operational amplifier, one end of the tenth resistor, one end of the eleventh resistor and one end of the twelfth resistor are all connected to the inverting input end of the first operational amplifier, the other end of the tenth resistor is connected to the detection unit, one end of the thirteenth resistor is connected to the detection unit, the other end of the thirteenth resistor is connected to the non-inverting input end of the second operational amplifier, one end of the fourteenth resistor and one end of the fifteenth resistor are connected to the inverting input end of the second operational amplifier, the other end of the fourteenth resistor is grounded, the other end of the fifteenth resistor and one end of the sixteenth resistor are both connected to the output end of the second operational amplifier, and the other end of the sixteenth resistor is connected to the voltage-controlled attenuation module.

[0024] An embodiment of the present application further provides a communication device, which includes the above-mentioned limiting circuit.

[0025] The present application provides a limiting circuit and a communication device, wherein the limiting circuit is provided with a voltage-controlled attenuation module and a voltage-controlled module, and the voltage-controlled module can flexibly adjust the attenuation value of the voltage-controlled attenuation module so as to adapt to the maximum input power requirements of different RF agile switches; at the same time, after the limiting module in this embodiment performs one limiting, the voltage-controlled attenuation module attenuates the RF signal after the limiting by the limiting module. In this process, there is no need to set multiple π-type attenuators to limit the maximum input power to the RF agile switch, thereby alleviating the problem that the π-type attenuator brings system noise to the receiving link and reduces the receiving sensitivity of the entire device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0027] Figure 1 This is a structural block diagram of the first embodiment of the limiting circuit provided in the embodiments of the present application.

[0028] Figure 2 This is a structural block diagram of the first limiter module and the second limiter module in the limiting circuit provided in an embodiment of the present application.

[0029] Figure 3 This is a structural block diagram of the second embodiment of the limiting circuit provided in the embodiment of the present application.

[0030] Figure 4 This is a structural block diagram of the limiting module and the voltage control module in the limiting circuit provided in an embodiment of the present application.

[0031] Figure 5 A circuit diagram of a limiting module, a voltage control module, and a voltage-controlled attenuation module in the limiting circuit provided in an embodiment of the present application.

[0032] Figure 6 A schematic diagram of the S parameters of the voltage-controlled attenuation module of the limiting circuit provided in an embodiment of the present application when receiving a low-power input RF signal.

[0033] Figure 7 A schematic diagram of the voltage-controlled voltage of the limiting circuit provided in an embodiment of the present application when receiving a low-power input RF signal.

[0034] Figure 8 A schematic diagram of the S parameters of the voltage-controlled attenuation module of the limiting circuit provided in an embodiment of the present application when receiving a high-power input RF signal.

[0035] Fig. 9 A schematic diagram of the voltage-controlled voltage of the limiting circuit provided in an embodiment of the present application when receiving a high-power input RF signal.

[0036] Fig.10A schematic diagram of the S parameters of the voltage-controlled attenuation module corresponding to the amplitude limiting circuit provided in the embodiment of the present application receiving a high-power input RF signal at a preset threshold voltage.

[0037] Fig.11 A schematic diagram of a voltage-controlled voltage corresponding to a high-power input RF signal received by a limiting circuit provided in an embodiment of the present application at a preset threshold voltage.

[0038] Fig.12 A schematic diagram of S parameters of a voltage-controlled attenuation module corresponding to a high-power input RF signal received by a limiting circuit provided in an embodiment of the present application at another preset threshold voltage.

[0039] Fig.13 A schematic diagram of a voltage-controlled voltage corresponding to a high-power input RF signal received by a limiting circuit provided in an embodiment of the present application at another preset threshold voltage. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of technical features indicated. The features specified as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present utility model, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0042] See also Figure 1 The present embodiment provides a limiting circuit, which includes a first limiter module 11, a second limiter module 12 and a fixed attenuator 13 connected in sequence, and the fixed attenuator 13 is also connected to the RF agile device 20. The first limiter module 11 is used to receive a RF signal of a certain amplitude, compress the signal amplitude of the RF signal and output a RF signal A1, and then the RF signal A1 is compressed again by the second limiter module 12 and outputs a RF signal A2, and then the fixed attenuator 13, such as a π-type attenuator, attenuates the RF signal A2 and outputs a RF signal A3 to the RF agile device 20.

[0043] See also Figure 2In a specific implementation, the first limiter module 11 includes a first limiter tube 111, and the second limiter module 12 includes a second limiter tube 121. The models of the first limiter tube 111 and the second limiter tube 121 can be GIB2015. When the maximum input power of the input RF signal limited by the first limiter tube 111 is +30dBm, the first limiter tube 111 can compress it to about +17 dBm to obtain the RF signal A1, and then the RF signal A1 is compressed to about +9dBm by the second limiter tube 121 to obtain the RF signal A2, and finally the RF signal A2 is attenuated to about +2dBm by the fixed attenuator 13.

[0044] See also Figure 3 , the embodiment of the present application also provides a limiting circuit, which includes a limiting module 100, a voltage-controlled attenuation module 200 and a voltage-controlled module 300, wherein the limiting module 100 is connected to the voltage-controlled attenuation module 200 and the voltage-controlled module 300 respectively, and the voltage-controlled module 300 is also connected to the voltage-controlled attenuation module 200. Among them, the limiting module 100 is used to reduce the signal amplitude of the received input RF signal and then output a first RF signal to the voltage-controlled attenuation module 200, and output a coupling signal to the voltage-controlled module 300 according to the first RF signal; the voltage-controlled attenuation module 200 is used to reduce the signal amplitude of the first RF signal to no more than a target threshold value according to a target attenuation value and then output a second RF signal; the voltage-controlled module 300 is used to output a voltage-controlled voltage according to the size of the coupling signal and a preset threshold voltage DAC1, so as to adjust the attenuation value of the voltage-controlled attenuation module 200 to the target attenuation value.

[0045] In this embodiment, by setting the voltage-controlled attenuation module 200 and the voltage-controlled module 300, the voltage-controlled module 300 can flexibly adjust the attenuation value of the voltage-controlled attenuation module 200 so as to adapt to the maximum input power requirements of different RF agile switches 20; at the same time, in this embodiment, after the limiting module 100 performs one limiting, the voltage-controlled attenuation module 200 attenuates the RF signal after the limiting by the limiting module 100. In this process, there is no need to set multiple π-type attenuators to limit the maximum input power to the RF agile switch 20, thereby alleviating the problem that the π-type attenuator brings system noise to the receiving link and reduces the receiving sensitivity of the entire device.

[0046] See also Figure 4In some embodiments, the voltage control module 300 includes a detection unit 310 and a voltage control unit 320. The detection unit 310 is connected to the limiter module 100, and the voltage control unit 320 is connected to the detection unit 310. The detection unit 310 is used to output a detection level according to the coupling signal, and the voltage control unit 320 is used to output a voltage-controlled voltage according to the magnitude of the detection level and the preset threshold voltage DAC1, so as to adjust the attenuation value of the voltage-controlled attenuation module 200 to the target attenuation value. In this embodiment, the detection unit 310 detects the power corresponding to the input RF signal according to the coupling signal, and then outputs a voltage value, i.e., the detection level, to the voltage control unit 320, so that the voltage control unit 320 can adjust the attenuation value of the voltage-controlled attenuation module 200 in combination with the preset threshold voltage DAC1.

[0047] In some embodiments, the limiting module 100 includes a limiting unit 110 and a coupling unit 120, the limiting unit 110 is connected to the coupling unit 120, the limiting unit 110 is used to reduce the signal amplitude of the received input RF signal and then output a first RF signal; the coupling unit 120 is used to output the first RF signal to the voltage-controlled attenuation module 200, and output a coupled signal to the detection unit 310 according to the first RF signal, so that the subsequent detection unit 310 outputs a detection level.

[0048] See also Figure 5 As an embodiment, the limiting unit 110 includes a limiting tube and a first inductor L1. The input end of the limiting tube U1 is used to access the input RF signal. The output end of the limiting tube U1 is connected to the coupling unit 120. One end of the first inductor L1 is connected to the output end of the limiting tube U1, and the other end of the first inductor L1 is grounded. The limiting tube U1 in this embodiment can be GIB2015. When the maximum input power of the limiting tube U1 is +30dBm, the limiting tube U1 can compress the signal amplitude of the input RF signal to about +17dBm.

[0049] As an embodiment, the coupling unit 120 includes a coupler U2, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, the input end of the coupler U2 is connected to the limiting unit 110, the coupling end of the coupler U2 is connected to one end of the first resistor R1 and one end of the fourth resistor R4, the other end of the first resistor R1 and one end of the second resistor R2 are grounded, the other end of the second resistor R2 is connected to the other end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the detection unit 310; the output end of the coupler U2 is connected to the voltage-controlled attenuation module 200, and the isolation end of the coupler U2 is grounded through the third resistor R3; the detection unit 310 includes a detection tube U3, the input end of the detection tube U3 is connected to the coupling unit 120, and the output end of the detection tube U3 is connected to the voltage control unit 320.

[0050] In this embodiment, the coupler U2 forms two outputs according to the first RF signal output by the limiting tube U1, one of which outputs a coupled signal to the detector tube U3 after coupling, and the other directly outputs the first RF signal to the voltage-controlled attenuation module 200. The detector tube U3 outputs a detection level such as a voltage value of 1V to the voltage control unit 320 according to the coupled signal, so that the voltage control unit 320 can adjust the attenuation value of the voltage-controlled attenuation module 200.

[0051] Please continue reading Figure 5 As an embodiment, the voltage control unit 320 includes a first operational amplifier A11 and a second operational amplifier A12, the inverting input terminal of the first operational amplifier A11 is connected to the third pin of the detector tube U3, the non-inverting input terminal of the first operational amplifier A11 is used to receive the preset threshold voltage DAC1, the output terminal of the first operational amplifier A11 is connected to the voltage-controlled attenuation module 200 and the inverting input terminal of the first operational amplifier A11, the non-inverting input terminal of the second operational amplifier A12 is connected to the output terminal of the detector tube U3, the inverting input terminal of the second operational amplifier A12 is grounded, and the output terminal of the second operational amplifier A12 is connected to the inverting input terminal of the second operational amplifier A12 and the voltage-controlled attenuation module 200.

[0052] In this embodiment, the detection level is output by the detector tube U3 to the first operational amplifier A11 and the second operational amplifier A12. The first operational amplifier A11 performs a subtraction proportional amplification on the detection level and the preset threshold voltage DAC1 and then outputs a first voltage-controlled voltage to control the RF path conduction impedance of the voltage-controlled attenuation module 200; the second operational amplifier A12 performs a proportional amplification in the same direction and then outputs a second voltage-controlled voltage to control the ground impedance of the voltage-controlled attenuation module 200, so that the attenuation value of the voltage-controlled attenuation module 200 reaches the target attenuation value. Then, after the first RF signal passes through the voltage-controlled attenuation module 200, the signal amplitude is attenuated to not more than the target threshold value, ensuring that the signal amplitude input to the RF agile converter 20 does not exceed the maximum input power requirement.

[0053] As an embodiment, the voltage control unit 320 further includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15 and a sixteenth resistor R16; one end of the eighth resistor R8 is connected to the voltage-controlled attenuation module 200, the other end of the eighth resistor R8 is connected to the output end of the first operational amplifier A11, one end of the ninth resistor R9 is used to access the preset threshold voltage DAC1, the other end of the ninth resistor R9 is connected to one end of the seventh resistor R7 and the non-inverting input end of the first operational amplifier A11, one end of the tenth resistor R10 and one end of the eleventh resistor R11 are connected to the output end of the first operational amplifier A11, One end of the 12th resistor R12 is connected to the inverting input terminal of the first operational amplifier A11, the other end of the 10th resistor R10 is connected to the detection unit 310, one end of the 13th resistor R13 is connected to the detection unit 310, the other end of the 13th resistor R13 is connected to the non-inverting input terminal of the second operational amplifier A12, one end of the 14th resistor R14 and one end of the 15th resistor R15 are connected to the inverting input terminal of the second operational amplifier A12, the other end of the 14th resistor R14 is grounded, the other end of the 15th resistor R15 and one end of the 16th resistor R16 are connected to the output terminal of the second operational amplifier A12, and the other end of the 16th resistor R16 is connected to the voltage-controlled attenuation module 200. In this embodiment, resistors and capacitors are correspondingly arranged at the in-phase input terminal, the inverting input terminal and the output terminal of the first operational amplifier A11 and the second operational amplifier A12 to adapt the first operational amplifier A11 and the second operational amplifier A12, thereby ensuring the normal operation of the two operational amplifiers.

[0054] As an embodiment, the voltage-controlled attenuation module 200 includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth resistor R5 and a sixth resistor R6. One end of the first capacitor C1 is connected to the coupling unit 120, the other end of the first capacitor C1 is connected to the anode of the third diode D3 through the second capacitor C2, the anode of the first diode D1 and one end of the third inductor L3 are connected to the other end of the first capacitor C1, the cathode of the first diode D1 is grounded through the fifth resistor R5, the other end of the third inductor L3 is connected to the output end of the second operational amplifier A12, one end of the fifth capacitor C5 is connected to the other end of the third inductor L3, and the other end of the fifth capacitor C5 is grounded; one end of the fourth inductor L4 is connected to the anode of the third diode D3, the other end of the fourth inductor L4 is connected to the output end of the first operational amplifier A11, one end of the seventh capacitor C7 is connected to the other end of the fourth inductor L4, and the other end of the seventh capacitor C7 is grounded; the cathode of the third diode D3 is connected to the cathode of the fourth diode D4 and the second inductor L2 The anode of the fourth diode D4 is connected to one end of the fifth inductor L5 and one end of the third capacitor C3, the other end of the third capacitor C3 is connected to one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is used to output the second RF signal, the anode of the second diode D2 is connected to one end of the fourth capacitor C4, the cathode of the second diode D2 is grounded through the sixth resistor R6, one end of the fifth inductor L5 is connected to the other end of the third capacitor C3, the other end of the fifth inductor L5 is connected to one end of the eighth capacitor C8 and the output end of the first operational amplifier A11, the other end of the eighth capacitor C8 is grounded, one end of the sixth inductor L6 is connected to one end of the fourth capacitor C4, the other end of the sixth inductor L6 is connected to one end of the sixth capacitor C6 and the output end of the second operational amplifier A12, and the other end of the sixth capacitor C6 is grounded.

[0055] Please also read Figure 6 and Figure 7 , Figure 6 Schematic diagram of S parameters of the voltage-controlled attenuation module 200 when the limiting circuit receives a low-power input RF signal. Figure 7 The figure is a schematic diagram of the voltage control voltage of the limiting circuit when receiving a low-power input RF signal. Among them, S21 refers to the insertion loss of the circuit, S11 refers to the port input echo, S22 refers to the port output echo, and S21 corresponds to Figure 6 S(2,1) in S11 corresponds to Figure 6 S(1,1) in S22 corresponds to Figure 6In this embodiment, when the frequency is 1.300 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -0.676 dB, S11 corresponds to -23.314 dB, and S22 corresponds to -23.314 dB; when the frequency is 1.950 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -0.763 dB, S22 corresponds to -24.330 dB, and S11 corresponds to -24.330 dB.

[0056] When the input RF signal of the limiting circuit in this embodiment is a low-power signal, the specific working process of the limiting circuit is as follows: the preset threshold voltage DAC1 is set to 1.13V, the input RF signal is a low-power signal of -3dBm, the limiting tube U1 does not work at this time, the power input to the detector tube U3 is -30dBm, the detector tube U3 outputs a voltage of 0.4V, the attenuation value of the voltage-controlled attenuation module 200 is about 0.7dB, the first operational amplifier A11 and the second operational amplifier A12 each output a voltage-controlled voltage, namely Vout1=1.351V, Vout2=0.633V, so that the corresponding RF path in the voltage-controlled attenuation module 200 is in a conductive state of two impedances. Correspondingly, in this embodiment, the limiting tube U1 does not work, the attenuation value of the voltage-controlled attenuation module 200 is about 0.7dB, and after being cascaded with the front-end circuit, the system noise is almost not increased, avoiding the problem of decreased receiving sensitivity.

[0057] Please also read Figure 8 and Fig. 9 , Figure 8 Schematic diagram of S parameters of the voltage-controlled attenuation module 200 when the limiting circuit receives a high-power input RF signal. Fig. 9 The figure is a schematic diagram of the voltage control voltage of the limiting circuit when receiving a strong power input RF signal. Among them, S21 refers to the insertion loss of the circuit, S11 refers to the port input echo, S22 refers to the port output echo, and S21 corresponds to Figure 8 S(2,1) in S11 corresponds to Figure 8 S(1,1) in S22 corresponds to Figure 8 In this embodiment, when the frequency is 1.300 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -20.338 dB, S22 corresponds to -35.192 dB, and S11 corresponds to -35.192 dB; when the frequency is 1.950 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -20.226 dB, S22 corresponds to -35.317 dB, and S11 corresponds to -35.317 dB.

[0058] In this embodiment, when the input RF signal of the limiting circuit is a high-power signal, the specific working process of the limiting circuit is as follows: the preset threshold voltage DAC1 is set to 1.13V. When the input RF signal is a strong signal of +30dBm, the limiting tube U1 outputs a first RF signal with a power of +17dBm after limiting. The power of the first RF signal input to the detector tube U3 after coupling by the coupler U2 is -10dBm. After that, the detector tube U3 outputs the detection level, that is, outputs a 1V voltage. At this time, the attenuation value of the voltage-controlled attenuation module 200 is about 20dB. The first operational amplifier A11 and the second operational amplifier A12 each output a voltage-controlled voltage, that is, Vout1=0.631V, Vout2=1.582V, so that the corresponding RF path in the voltage-controlled attenuation module 200 is in the conduction state of two impedances.

[0059] Please also read Fig.10 , Fig.11 , Fig.12 and Fig.13 , wherein the preset threshold voltage DAC1 can be set differently as needed. Fig.10 The figure is a schematic diagram of the S parameters of the voltage-controlled attenuation module 200 corresponding to the amplitude limiting circuit receiving a high-power input RF signal at a preset threshold voltage. Fig.11 The schematic diagram is a voltage control voltage corresponding to a high-power input RF signal received by the limiter circuit at a preset threshold voltage. Fig.12 A schematic diagram of S parameters of the voltage-controlled attenuation module 200 corresponding to the amplitude limiting circuit provided in the embodiment of the present application receiving a high-power input RF signal at another preset threshold voltage; Fig.13 Schematic diagram of the voltage control voltage corresponding to the input RF signal of the limiting circuit provided in the embodiment of the present application when receiving a high-power input RF signal at another preset threshold voltage. Among them, S21 refers to the insertion loss of the circuit, S11 refers to the port input echo, S22 refers to the port output echo, and S21 corresponds to Fig.10 and Fig.12 S(2,1) in S11 corresponds to Fig.10 and Fig.12 S(1,1) in S22 corresponds to Fig.10 and Fig.12 S(2,2) in . Fig.10 As shown, when the frequency is 1.300 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -32.275 dB, S22 corresponds to -24.903 dB, and S11 corresponds to -24.903 dB; when the frequency is 1.950 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -31.017 dB, S22 corresponds to -24.693 dB, and S11 corresponds to -24.693 dB. Fig.12As shown, when the frequency is 1.300 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -9.576 dB, S22 corresponds to -11.819 dB, and S11 corresponds to -11.819 dB; when the frequency is 1.950 GHz, S21 in the voltage-controlled attenuation module 200 corresponds to -9.651 dB, S22 corresponds to -11.924 dB, and S11 corresponds to -11.924 dB.

[0060] For example: when the input RF signal is a strong signal of +30dBm, the limiting tube U1 limits the output power of the first RF signal to +17dBm, and the input detection tube U3 power is -10dBm. After that, the detection tube U3 outputs the detection level, that is, outputs a 1V voltage. Different threshold voltage attenuation states are preset. When the threshold voltage DAC1 is preset to 0.5V, the attenuation value is about 31dB. Fig.10 and Fig.11 When the preset voltage threshold is 1.19V, the attenuation value is about 10dB. Fig.12 and Fig.13 As shown. In the present application, the preset threshold voltage DAC1 can be flexibly set by the digital-to-analog converter to achieve the required attenuation value adjustment. Moreover, the voltage-controlled attenuation module 200 in this embodiment has a faster response time than the digital step attenuator.

[0061] The embodiment of the present application also provides a communication device, which includes a radio frequency agile switch and the above-mentioned limiting circuit, wherein the limiting circuit provides a radio frequency signal to the radio frequency agile switch and ensures that the radio frequency signal input to the radio frequency agile switch does not exceed the maximum input power requirement of the radio frequency agile switch. Since the limiting circuit is described in detail above, it will not be repeated here.

[0062] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0063] The limiting circuit provided in the embodiments of the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A limiting circuit, characterized in that: The limiting circuit comprises: A limiting module, the limiting module is used to reduce the signal amplitude of the received input radio frequency signal and then output a first radio frequency signal, and output a coupled signal according to the first radio frequency signal; A voltage-controlled attenuation module, the voltage-controlled attenuation module is connected to the limiting module; the voltage-controlled attenuation module is used to reduce the signal amplitude of the first radio frequency signal to no greater than a target threshold value according to a target attenuation value and then output a second radio frequency signal; A voltage control module, the voltage control module is connected to the limiting module and the voltage-controlled attenuation module respectively; the voltage control module is used to output a voltage-controlled voltage according to the size of the coupling signal and a preset threshold voltage to adjust the attenuation value of the voltage-controlled attenuation module to the target attenuation value.

2. The limiting circuit according to claim 1, characterized in that: The voltage control module comprises: A detection unit, the detection unit is connected to the limiting module, and the detection unit is used to output a detection level according to the coupled signal; A voltage control unit is connected to the detection unit, and is used to output a voltage-controlled voltage according to the size of the detection level and the preset threshold voltage to adjust the attenuation value of the voltage-controlled attenuation module to the target attenuation value.

3. The limiting circuit according to claim 2, characterized in that: The limiting module comprises: A limiting unit, the limiting unit is used to reduce the signal amplitude of the received input radio frequency signal and then output a first radio frequency signal; A coupling unit, wherein the coupling unit is connected to the limiting unit, and the coupling unit is used to output the first radio frequency signal to the voltage-controlled attenuation module, and output the coupled signal to the detection unit according to the first radio frequency signal.

4. The limiting circuit according to claim 3, characterized in that: The detection unit comprises a detection tube, an input end of the detection tube is connected to the coupling unit, and an output end of the detection tube is connected to the voltage control unit.

5. The limiter circuit according to claim 4, characterized in that: The voltage control unit includes a first operational amplifier and a second operational amplifier, the inverting input terminal of the first operational amplifier is connected to the voltage output terminal of the detector tube, the non-inverting input terminal of the first operational amplifier is used to receive the preset threshold voltage, the output terminal of the first operational amplifier is connected to the voltage-controlled attenuation module and the inverting input terminal of the first operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the detector tube, the inverting input terminal of the second operational amplifier is grounded, and the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier and the voltage-controlled attenuation module.

6. The limiter circuit according to claim 3, characterized in that: The coupling unit includes a coupler, a first resistor, a second resistor, a third resistor and a fourth resistor, the input end of the coupler is connected to the limiting unit, the coupling end of the coupler is connected to one end of the first resistor and one end of the fourth resistor, the other end of the first resistor and one end of the second resistor are grounded, the other end of the second resistor is connected to the other end of the fourth resistor, and the other end of the fourth resistor is connected to the detection unit; the output end of the coupler is connected to the voltage-controlled attenuation module, and the isolation end of the coupler is grounded through the third resistor.

7. The limiting circuit according to claim 3, characterized in that: The limiting unit includes a limiting tube and a first inductor, the input end of the limiting tube is used to access the input RF signal, the output end of the limiting tube is connected to the coupling unit, one end of the first inductor is connected to the output end of the limiting tube, and the other end of the first inductor is grounded.

8. The limiting circuit according to claim 5, characterized in that: The voltage-controlled attenuation module includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a first diode, a second diode, a third diode, a fourth diode, a fifth resistor and a sixth resistor; One end of the first capacitor is connected to the coupling unit, the other end of the first capacitor is connected to the anode of the third diode through the second capacitor, the anode of the first diode and one end of the third inductor are connected to the other end of the first capacitor, the cathode of the first diode is grounded through the fifth resistor, the other end of the third inductor is connected to the output end of the second operational amplifier, one end of the fifth capacitor is connected to the other end of the third inductor, and the other end of the fifth capacitor is grounded; one end of the fourth inductor is connected to the anode of the third diode, the other end of the fourth inductor is connected to the output end of the first operational amplifier, one end of the seventh capacitor is connected to the other end of the fourth inductor, and the other end of the seventh capacitor is grounded; the cathode of the third diode is connected to the cathode of the fourth diode and the second inductor. one end of the fifth inductor is connected to the output terminal of the first operational amplifier, the other end of the fifth inductor is connected to the output terminal of the first operational amplifier, the other end of the eighth capacitor is connected to the output terminal of the first operational amplifier, the other end of the eighth capacitor is grounded, the one end of the sixth inductor is connected to the one end of the fourth capacitor, the other end of the sixth inductor is connected to the output terminal of the second operational amplifier, and the other end of the sixth capacitor is grounded.

9. The limiter circuit according to claim 5, characterized in that: The voltage control unit further includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor and a sixteenth resistor; One end of the eighth resistor is connected to the voltage-controlled attenuation module, the other end of the eighth resistor is connected to the output end of the first operational amplifier, one end of the ninth resistor is used to access the preset threshold voltage, the other end of the ninth resistor is connected to one end of the seventh resistor and the non-inverting input end of the first operational amplifier, one end of the tenth resistor, one end of the eleventh resistor and one end of the twelfth resistor are all connected to the inverting input end of the first operational amplifier, the other end of the tenth resistor is connected to the detection unit, one end of the thirteenth resistor is connected to the detection unit, the other end of the thirteenth resistor is connected to the non-inverting input end of the second operational amplifier, one end of the fourteenth resistor and one end of the fifteenth resistor are connected to the inverting input end of the second operational amplifier, the other end of the fourteenth resistor is grounded, the other end of the fifteenth resistor and one end of the sixteenth resistor are both connected to the output end of the second operational amplifier, and the other end of the sixteenth resistor is connected to the voltage-controlled attenuation module.

10. A communication device, characterized in that: The communication device comprises the limiting circuit according to any one of claims 1-9.

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