82results about "Limiting amplitude using diodes" patented technology

The invention provides a high-power amplitude limiting circuit based on a gallium nitride Schottky diode, and relates to the technical field of radio frequency microwave integrated circuits. Comprising an input port of a high-power amplitude limiting circuit, a capacitor C1, a post-start detection network and a pre-stage amplitude limiting network, and the pre-start detection network, a capacitor C2, a post-stage amplitude limiting network, a capacitor C3 and an output port of the high-power amplitude limiting circuit are sequentially connected in series. The front-stage amplitude limiting network comprises a plurality of first PIN diodes which are connected in parallel, the number of the rear-stage amplitude limiting networks is one or more, and the plurality of rear-stage amplitude limiting networks are connected in series; the anodes of the plurality of first PIN diodes are connected with the output end of the post-start detection network and the input end of the pre-start detection network, and the cathodes of the plurality of first PIN diodes are grounded. Therefore, the high-power amplitude limiting circuit based on the gallium nitride Schottky diode can reach a myriawatt-level amplitude limiting level, the occupied area is smaller, the power endurance capability is more stable, and the insertion loss is smaller.

The invention discloses a K-band amplitude-limiting low-noise amplifier, and belongs to the technical field of radio frequency microelectronics. The circuit comprises an input matching module, a diode amplitude limiting module, an inter-stage matching module, a low-noise amplification module and an output matching module which are cascaded in sequence, the input matching module is used for realizing impedance matching between a radio frequency signal input end and the diode amplitude limiting module and transmitting a radio frequency signal; the diode amplitude limiting module is used for limiting the amplitude of the radio frequency signal and transmitting the radio frequency signal; the inter-stage matching module is used for realizing impedance matching between the diode amplitude limiting module and the low-noise amplification module; the low-noise amplification module is used for carrying out amplification processing on the radio frequency signal after amplitude limiting and transmitting the radio frequency signal; and the output matching module is used for realizing impedance matching between the low-noise amplification module and the radio frequency signal output end and outputting the amplified radio frequency signal. According to the invention, the amplitude of the input signal can be limited, so that the amplitude is kept in a bearable range of the low-noise amplification circuit, and the stability and reliability of the whole system are ensured.

The invention provides a high-power amplitude limiter with a filtering characteristic. The high-power amplitude limiter comprises a first amplitude limiting module connected with an input port, a second amplitude limiting module connected with an output port and an intermediate cascade module. The first amplitude limiting module comprises a first amplitude limiting circuit and a first reactance module; the first amplitude limiting circuit and the first reactance module are connected in series to a main transmission line of the amplitude limiter. The second amplitude limiting module comprises a second amplitude limiting circuit and a second reactance module; the second amplitude limiting circuit and the second reactance module are connected in series to the main transmission line of the amplitude limiter; the two ends of the middle cascade module are connected in series with inductive reactance elements and then connected to the amplitude limiter main transmission line, and the middle of the middle cascade module is connected in parallel with capacitive elements and then grounded. According to the technical scheme, the original in-band excellent electromagnetic protection characteristic of the amplitude limiter can be ensured while the filtering characteristic is realized, the performance deterioration of a radio frequency receiving signal caused by cascade mismatch of the amplitude limiter and a radio frequency channel post-stage filter is avoided, and the total volume ratio of a radio frequency channel electromagnetic protection device is effectively reduced.

The electromagnetic protection amplitude limiter comprises a waveguide plasma amplitude limiter, a solid-state PIN tube amplitude limiter and a third-stage amplitude limiting assembly, the waveguide plasma amplitude limiter is connected with the solid-state PIN tube amplitude limiter in series, the solid-state PIN tube amplitude limiter is connected with the third-stage amplitude limiting assembly in series, and the solid-state PIN tube amplitude limiter is connected with the third-stage amplitude limiting assembly in series. The third-stage amplitude limiting assembly comprises a microwave switch A, a low-noise amplifier, a fixed attenuator and a microwave switch B. The low-noise amplifier and the fixed attenuator are connected in parallel, the microwave switch A is connected with the input end of the low-noise amplifier and the input end of the fixed attenuator in series, and the microwave switch B is connected with the output end of the low-noise amplifier and the output end of the fixed attenuator in series. The waveguide plasma amplitude limiter and the solid PIN tube amplitude limiter are connected in series, and the microwave switch adopts a series-parallel structural design, so that the problems of long response time and large peak leakage power of the plasma amplitude limiter are solved, and the electromagnetic protection amplitude limiting requirement that an amplitude limiting level does not cause damage to a low-noise amplifier or a post-stage circuit is ensured.

The utility model provides an adjustable amplitude limiter structure and radio frequency equipment, and relates to the technical field of radio frequency. According to the invention, multiple stages of diode discharge links formed by forward series connection of multiple diodes are arranged, so that respective middle connection points of two adjacent stages of diode discharge links are connected through a microstrip line, and respective anode connection ends of the multiple stages of diode discharge links are externally connected with forward bias voltage signals through the same choke inductor; and meanwhile, the respective cathode connecting ends of the multistage diode discharge links are grounded, and at the moment, the actual voltage values of the forward bias voltage signals can be adjusted, so that the multistage diode discharge links can be grounded under the action of different forward bias voltage signals. And the amplitude limiting circuit is used for carrying out amplitude limiting processing of different degrees on the radio frequency input signal acquired by the input matching circuit so as to dynamically adjust the amplitude limiting level of the corresponding amplitude limiter structure, so that the corresponding radio frequency output signal meets the input power requirements of the rear-end amplifier of different degrees.

The invention relates to a high-power microwave amplitude limiting protection circuit with high power capacity, and belongs to the field of strong electromagnetic pulse protection. The three-level PIN pair transistor amplitude limiting circuit and the eight-order hairpin type microstrip filter circuit are carried on the dielectric substrate, the first blocking capacitor is connected between the input end of the amplitude limiting protection circuit and the three-level PIN pair transistor amplitude limiting circuit, and the second blocking capacitor is connected between the three-level PIN pair transistor amplitude limiting circuit and the eight-order hairpin type microstrip filter circuit. The output end of the amplitude limiting protection circuit is connected with the eight-order hairpin type microstrip filter circuit. The invention has the advantages of large power capacity, small peak leakage, small starting limit level and low amplitude limiting level, can effectively suppress interference signals coupled into the receiving end of the wireless communication equipment by high-power microwaves, and improves the anti-interference capability of the wireless communication equipment under the radiation of the high-power microwaves.

The invention discloses a ferrite and solid state combined amplitude limiting circuit and a high-power microwave front door protection device, and belongs to the field of microwave devices.The combined amplitude limiting circuit comprises a ferrite substrate, and a ferrite amplitude limiting circuit and a solid state amplitude limiting circuit which are connected with each other are arranged on the front face of the ferrite substrate. The solid-state amplitude limiting circuit comprises two amplitude limiting diodes and two transmission lines, an inductor is arranged between the two transmission lines, one amplitude limiting diode is connected with an output transmission line, and the other amplitude limiting diode is connected with the output of the microstrip amplitude limiting circuit through the transmission line; the high-power microwave front door protection device has high power capacity (hundred kW magnitude), fast response and recovery time (several ns) and high amplitude limiting isolation (higher than 32 dB) in the HPM electromagnetic environment, the ideal high-power microwave front door comprehensive protection effect is achieved, the size of the device is small, and the device can be applied to microwave receiver strong electromagnetic pulse engineering protection.

The application provides an amplifier current-limiting control method for fusing power regulation and load characteristic monitoring, comprising: realizing controllable front-stage signal through differential input and band-pass clamping, establishing voltage, current and multi-point temperature monitoring and combining overvoltage detection to generate out-of-limit indication, setting voltage and current upper limit in silicon-controlled voltage regulating module and executing voltage reduction and current limiting, realizing orderly switching through front-stage shutdown and relay stable control when impedance gear is switched, keeping front-stage closed and shutting down power drive when out-of-limit continues to exist, and until monitoring quantity recovers to safe range. Through the collaborative design of "source power limiting, state monitoring, orderly switching and linkage protection", the application effectively suppresses transient impact, shortens protection response time, reduces distortion accumulation, and realizes the unity of high-power output and high reliability of wide-band multi-gear amplifier.

A near-field transmitter includes a power amplifier, a resonant network, an envelope detector, and an antenna tuning circuit. The power amplifier has an input for receiving a communication signal, and an output for providing a differential output signal. The resonant network is coupled to the output of the power amplifier and has a tunable reactive element tuned by a tuning signal. The envelope detector is coupled to the output of the power amplifier for providing an envelope signal in response to the differential output signal. The antenna tuning circuit is for adjusting the tuning signal in response to the envelope signal.

To provide a semiconductor device capable of measuring a minute current.SOLUTION: In a semiconductor device including an operational amplifier and a diode element. an inverting input terminal of the operational amplifier and an input terminal of the diode element are electrically connected to a first terminal to which a current is input, and an output terminal of the operational amplifier and an output terminal of the diode element are electrically connected to a second terminal from which a voltage is output. As the diode element, a diode-connected transistor including a metal oxide in a channel formation region is used. Since an off-state current of the transistor is extremely low, a minute current can be caused to flow between the first terminal and the second terminal. Thus, by outputting a voltage from the second terminal, a minute current flowing from this voltage through the first terminal can be estimated.SELECTED DRAWING: Figure 3

The disclosure provides a self-detection multi-stage limiter based on micro-assembly and a preparation method thereof. The limiter comprises a ceramic tube shell, a substrate, and a front-stage power detection processing circuit and a rear-stage leakage power processing circuit fixed on one side surface of the substrate based on a micro-assembly process. The rear-stage leakage power processing circuit is a monolithic microwave integrated circuit, and the monolithic microwave integrated circuit is integrated with M series limiting units in series. Each limiting unit comprises two element strings in reverse parallel connection, and each element string comprises a plurality of gallium nitride Schottky diodes in series connection. The self-detection limiter based on the micro-assembly process can realize a fast response time, clamp the leakage peak power leaked after the front-stage processing by using the rear-stage leakage power processing circuit, and realize flexible adjustment of the amplitude threshold and the leakage level by adjusting the number of limiting unit stages or the number of GaN SBDs in series connection in the limiting unit, so as to facilitate matching of the signal power range and the protection requirements of different use scenarios.

A clamping circuit that may be used to provide efficient and effective voltage clamping in an RF front end. The clamping circuit comprises two series coupled signal path switches and a bypass switch coupled in parallel with the series coupled signal path switches. A diode is coupled from a point between the series coupled signal path switches to a reference potential. In addition, an output selection switch within an RF front end has integrated voltage clamping to more effectively clamp the output voltage from the RF front end. Additional output clamping circuits can be used at various places along a direct gain signal path, along an attenuated gain path and along a bypass path.

The application provides a limiter circuit, which comprises a plurality of transmission lines connected in series, one end of the transmission lines is used as an input end of a radio frequency signal, the other end of the transmission lines is connected with an input end of an amplifier, and an output end of the amplifier is used as an output end of the radio frequency signal; a limiter branch is connected between adjacent transmission lines and the amplifier in sequence, and the parasitic capacitance of each limiter branch is equal; a limiter bias circuit is electrically connected with each limiter branch, and is used for making the opening power voltage of each limiter branch equal. According to the application, the size of each limiter branch is adjusted according to the uneven distribution of current, so that the current density of each limiter branch is balanced, and the insertion loss and impedance matching can be effectively improved, and the bandwidth is improved under the premise of realizing the current density balance and improving the power protection ability.

The invention relates to the technical field of audio signal processing, in particular to an audio voltage limiter based on a Schottky diode and application of the audio voltage limiter, the audio voltage limiter comprises a diode threshold value unit and a voltage division attenuation unit, the diode threshold value unit sets a voltage limit threshold value through diode type combination; the voltage division attenuation unit forms an N: 1 voltage division network by two resistors so as to realize compression ratio control; the diode threshold unit is formed by at least two diodes which are reversely connected in parallel or are subjected to bridge rectification; the voltage limiter breaks through the cost and volume limitation of the traditional voltage limiter, realizes efficient dynamic control through the extremely simple combination of the diodes and the resistors, and is particularly suitable for the scenes sensitive to the cost, such as automobile audio and the like. The modular design supports flexible adjustment of a threshold value, and a signal protection scheme with high cost performance is provided for the fields of vehicle-mounted sound equipment, consumer electronics and the like.

The invention relates to the technical field of radio frequency devices, in particular to an amplitude limiter circuit structure integrated with a filtering function by a gallium arsenide process, and the circuit sequentially comprises a 50-ohm microstrip input matching section, a first-stage amplitude limiting filtering unit, a second-stage amplitude limiting filtering unit and an output matching section along a main transmission line, in the first stage, three forward PIN diodes and three reverse PIN diodes are stacked and connected to a main circuit in parallel, high power tolerance and symmetrical amplitude limiting capacity are achieved, and two low-frequency transmission zero points are formed by fusing a micro-strip grounding branch knot and an MIM capacitor resonator; in the second stage, two anti-parallel PIN diodes are matched with a grounding inductor to form a third transmission zero point, three groups of resonant structures are integrated, six transmission zero points are introduced, the filtering performance in a 12-18GHz frequency band is remarkably enhanced, a PIN diode parasitic capacitor and a microstrip inductive structure are skillfully utilized by the circuit to cooperatively realize filtering, extra passive elements are not needed, and the cost is low. The method is suitable for integrated protection of sensitive devices in a high-frequency radar and communication system.

A broadband low insertion loss limiter chip based on a hybrid π-type topology, belonging to the technical field of microwave passive devices, solves the problems of high small-signal insertion loss, narrow operating bandwidth and large size of existing microwave limiters; by replacing the quarter-wavelength transmission line between the limiter circuits with a capacitive-loaded hybrid π-type structure, the electrical lengths of the first and second tapered U-shaped transmission lines in the two hybrid π-type structures are much less than 90° and are bent, reducing the area of the limiter chip; the first-stage limiter circuit reduces the total equivalent capacitance, thereby reducing the insertion loss; the electrical length of the transmission line is shortened, and its physical length is correspondingly shortened, reducing the insertion loss; in the two hybrid π-type structures, the total turn-off capacitance of each stage of the limiter circuit is absorbed into the hybrid π-type structure, making the limiter equivalent to a quasi-50-ohm transmission line model at small signals, thereby eliminating the influence of the turn-off capacitance reactance loaded on the transmission channel on impedance matching and expanding the operating bandwidth of the limiter.

The invention relates to a high-power dual-coupling detection amplitude limiting circuit, which belongs to the field of microwave amplitude limiters and comprises a pre-stage amplitude limiting circuit, an auxiliary detection network and a post-stage amplitude limiting circuit which are sequentially connected along a main signal path, and the auxiliary detection network is used for reducing the power input to the post-stage amplitude limiting circuit by coupling input power before the detector tube D1 of the pre-stage amplitude limiting circuit is not fully conducted, and assisting the conduction of the PIN tube in the pre-stage amplitude limiting circuit. According to the high-power dual-coupling detection amplitude limiting circuit, the auxiliary detection network is added on the basis of a traditional semi-active circuit structure, and excessive radio-frequency power leaked into the rear-stage amplitude limiting circuit is coupled out from a main signal path through the auxiliary detection network before a detector tube of the front-stage amplitude limiting circuit is not fully conducted; therefore, the input power of the PIN tube in the post-stage amplitude limiting circuit is reduced, and the PIN tube is not burnt down; and meanwhile, the part of power can be used for assisting the conduction of a PIN tube in preceding stage amplitude limiting.

A semiconductor device capable of measuring a minute current is provided. The semiconductor device includes an operational amplifier and a diode element. An inverting input terminal of the operational amplifier and an input terminal of the diode element are electrically connected to a first terminal to which current is input, and an output terminal of the operational amplifier and an output terminal of the diode element are electrically connected to a second terminal from which voltage is output. A diode-connected transistor that includes a metal oxide in a channel formation region is used as the diode element. Since the off-state current of the transistor is extremely low, a minute current can flow between the first terminal and the second terminal. Thus, when voltage is output from the second terminal, a minute current that flows through the first terminal can be estimated from the voltage.

The invention discloses a DC-DC converter control circuit suitable for a high pulse load, and belongs to the field of DC-DC converter control circuits, and the DC-DC converter control circuit comprises a voltage outer loop compensation circuit, a current amplitude limiting circuit, a current inner loop compensation circuit and a pulse width modulation circuit. The output end of the voltage outer loop compensation circuit is connected with one end of the current amplitude limiting circuit, the other end of the current amplitude limiting circuit is connected with the input end of the current inner loop compensation circuit, and the output end of the current inner loop compensation circuit is connected with the pulse width modulation circuit. According to the invention, the current amplitude limiting circuit and the loop compensation circuit are utilized to realize closed-loop regulation of the output inductive current, so that the capacity of outputting the capacitor of the converter is improved, the current response speed is accelerated, the stable output capacity and reliability of the converter are ensured, and the adaptability of a high-pulse load working condition is improved.

The invention belongs to the technical field of radio and microwaves, and discloses a microwave amplitude limiting device capable of removing peak leakage. According to the invention, through skillfully combining the coupling and resonance principles, quick response can be realized at the moment when a strong signal arrives, and the time window of energy leakage is obviously reduced. Compared with a traditional microwave amplitude limiter, the microwave amplitude limiter has the advantages that the response speed is higher, the response to strong signals can be made in an extremely short time, and therefore the risk of sharp point leakage is greatly reduced; the device provided by the invention is high in design flexibility, and can be optimized and adjusted according to different working frequency bands and signal characteristics so as to adapt to diversified application scenes; the device is compact in structure and can be easily integrated into an existing receiving link, large-scale transformation of the system is not needed, and the overall reliability and stability of the receiving link are further guaranteed.

The invention relates to the technical field of liquid level measurement, in particular to a pulse signal processing circuit and a magnetostrictive liquidometer, and the pulse signal processing circuit comprises an amplitude limiting module which is used for carrying out amplitude limiting processing on a first voltage signal and a second voltage signal transmitted by an induction coil of a magnetostrictive sensor, the first voltage signal is a voltage signal obtained according to an induction pulse signal, and the second voltage signal is a voltage signal obtained according to a strain pulse signal; the signal amplification module is connected with the output of the amplitude limiting module, amplifies the output and outputs the amplified output to a time-to-digital converter of the magnetostriction sensor; according to the pulse signal processing circuit, the interference of the induction pulse signal on the signal processing process of the time-to-digital converter can be well reduced.

The invention discloses an active amplitude limiting and filtering integrated module for a T / R assembly of phased array equipment. The module comprises first to fourth level LC resonance circuits, a PIN tube, a control circuit, an input port, an output port and a control port. The input port is connected with one end of the first-stage LC resonance circuit, and the other end of the first-stage LC resonance circuit is sequentially connected with one end of the second-stage LC resonance circuit, the anode of the PIN tube, one end of the third-stage LC resonance circuit and one end of the fourth-stage LC resonance circuit; the other end of the second-stage LC resonance circuit is grounded, the cathode of the PIN tube is grounded, the other end of the third-stage LC resonance circuit is grounded, and the other end of the fourth-stage LC resonance circuit is connected with an output port; one end of the control circuit is connected with the anode of the PIN tube, and the other end is connected with the control port. According to the invention, the integrated design is adopted, the size is small, the insertion loss is small, the anti-emission leakage signal burning performance of the receiving channel of the T / R assembly is improved, and the safety and stability of the T / R assembly are enhanced.

A clamping circuit that may be used to provide efficient and effective voltage clamping in an RF front end. The clamping circuit comprises two series coupled signal path switches and a bypass switch coupled in parallel with the series coupled signal path switches. A diode is coupled from a point between the series coupled signal path switches to a reference potential. In addition, an output selection switch within an RF front end has integrated voltage clamping to more effectively clamp the output voltage from the RF front end. Additional output clamping circuits can be used at various places along a direct gain signal path, along an attenuated gain path and along a bypass path.

The invention relates to the technical field of microwave passive devices, and provides a collaborative fusion-based adjustable amplitude limiting filter chip, which comprises a main transmission line, and a first-stage amplitude limiting circuit, a quarter-wavelength microstrip line TL1, a second-stage adjustable amplitude limiting circuit, an open-circuit quarter-wavelength microstrip line TL3 and a lumped parallel resonator which are loaded on the main transmission line and are sequentially connected, and the second-stage adjustable amplitude limiting circuit is loaded with an adjustable bias voltage source VDC. According to the chip designed by the invention, a filtering function is fused in an amplitude limiting circuit, and an amplitude limiting level adjustable function is realized while stopband suppression and circuit area are optimized.

To avoid deterioration of power limit performance of a RF limiter circuit that can avoid decrease in a voltage applied between an anode and a cathode of a diode due to an influence of parasitic inductance and that can be applied to RF receivers or the like.SOLUTION: A RF limiter circuit 10 includes a diode 11 and a RF chalk 12. A ground side of the RF limiter circuit 10 is connected to the ground via the RF chalk 12. In the RF limiter circuit 10, the RF chalk 12 is used for connection to a circuit return (ground) so that an influence of parasitic inductance is reduced. When a RF signal at a voltage VRF is input into the RF limiter circuit, a RF voltage VRF is applied to an anode of the diode. While a cathode of the diode is connected to the ground, DC resistance between return and ground becomes zero (0 Ω) by the RF chalk. In addition, RF resistance between return and ground becomes infinite (∞ Ω) by the RF chalk.SELECTED DRAWING: Figure 1

The present invention relates to the technical field of radio frequency microwave circuits, and in particular discloses a semi-active limiting circuit and method, including an input port and an output port of the semi-active limiting circuit, the semi-active limiting circuit also including a limiting network and a parallel detection network, the input end of the limiting network is connected to the input port, the output end of the limiting network is connected to the output port, and the parallel detection network is connected in parallel with the limiting network; the input port is used to receive an input signal; the parallel detection network is used to provide a bias signal to the limiting network when the power of the input signal is greater than a preset threshold; the limiting network is used to limit the input signal based on the bias signal, and output the limiting signal through the output port. The above-mentioned semi-active limiting circuit eliminates the complex coupling detection network compared to the traditional limiting circuit, and can effectively reduce the circuit insertion loss.

A voltage limiting circuit for a power amplifier that includes a diode circuit, a bias circuit to generate a bias voltage, and a sink circuit. The diode circuit is coupled to an output of an amplification stage of the power amplifier and configured to provide a conductive path from the output when an output voltage of the amplification stage exceeds a predetermined threshold. The sink circuit includes an attenuator, coupled to the diode circuit and the bias circuit, and is configured to reduce the bias voltage when the output voltage exceeds the predetermined threshold to thereby limit the output voltage, and the attenuator is configured to reduce a feedback of the output voltage routing through the sink circuit.

The invention discloses an ultra-wideband high-power-resistance amplitude limiting switch multifunctional chip, and relates to the technical field of amplitude limiting switches and integrated circuits. The chip comprises a PIN amplitude limiter and a single-pole four-throw PIN switch, the PIN amplitude limiter equally divides the power of a radio frequency input signal into two paths to improve the power capacity of the amplitude limiter, adjusts the amplitude limiting level through an anti-parallel diode, and transmits an amplitude limiting radio frequency input signal to the single-pole four-throw PIN switch; according to the single-pole four-throw PIN switch, a spiral inductor is adopted, resistors are introduced between coils of the spiral inductor to eliminate resonance points caused by parasitic capacitance and expand bandwidth, four corresponding branches are turned on or turned off according to four control voltages, and then an amplitude limiting radio frequency input signal is transmitted to the low-noise amplifier according to the turned-on branches. The power capacity of the amplitude limiter can be improved, the amplitude limiting level can be adjusted, and the bandwidth can be expanded while the amplitude limiting of the radio frequency input signal is realized.

The present invention discloses a K-band limiting low-noise amplifier, which belongs to the field of radio frequency microelectronics technology. The amplifier comprises an input matching module, a diode limiting module, an inter-stage matching module, a low-noise amplifier module, and an output matching module, which are sequentially connected in cascade. The input matching module is used to achieve impedance matching between the radio frequency signal input end and the diode limiting module, and transmit the radio frequency signal. The diode limiting module is used to limit the radio frequency signal and transmit it. The inter-stage matching module is used to achieve impedance matching between the diode limiting module and the low-noise amplifier module. The low-noise amplifier module is used to amplify and transmit the limited radio frequency signal. The output matching module is used to achieve impedance matching between the low-noise amplifier module and the radio frequency signal output end, and output the amplified radio frequency signal. The present invention can limit the amplitude of the input signal so that it remains within the range that the low-noise amplifier circuit can withstand, thereby ensuring the stability and reliability of the entire system.

The invention discloses a multistage microwave amplitude limiting circuit and a passive amplitude limiter. The multi-stage microwave amplitude limiting circuit is a multi-stage microwave amplitude limiting circuit of a gallium nitride Schottky diode adopting Schottky contact metal with different work functions and comprises a multi-stage amplitude limiting structure formed by cascading a plurality of amplitude limiting structures, and each stage of amplitude limiting structure comprises the gallium nitride Schottky diode adopting Schottky contact metal with different work functions. In the multi-stage amplitude limiting structure, Schottky metals with different work functions are used for modulating the turn-on voltage, so that the turn-on voltage of a diode in each stage of amplitude limiting structure is decreased progressively, and the lower amplitude limiting power of a high-power input signal is decreased progressively step by step. According to the invention, gallium nitride Schottky diodes of Schottky metal with different work functions are used in different stages of the amplitude limiting circuit, so that the power capacity is improved, the insertion loss is reduced, the response time and the recovery time are reduced, and the amplitude limiter can effectively protect a post-stage circuit under high-power input.