A limiting circuit

Abstract

The present application discloses a limiting circuit, which includes: a signal input terminal, a signal output terminal, at least one switch tube and at least one control unit; wherein at least one control unit is used to control the on and off of at least one switch tube; at least one switch tube is used to weaken the power of the radio frequency signal received by the signal input terminal in the on state and then output it through the signal output terminal. The limiting circuit disclosed in the present application uses a power detector to control the on and off of a FET to reduce the signal power at the signal receiving terminal, and the switch tubes in the limiting circuit can be connected in series or in parallel, and can be used to manufacture a small-sized limiting device.

Description

Technical Field

[0001] The present application relates to radio frequency front-end integrated circuit technology in the field of radio communication and radar technology, and in particular to a limiting circuit. Technical Background

[0002] In wireless communication, radar, electronic countermeasures and other systems, the transmitter transmits radio signals and the receiver receives radio signals. Generally speaking, the greater the transmitter transmission power, the more conducive it is to long-distance communication and detection. However, due to the demand for high sensitivity, the low-noise receiving circuit at the front end of the receiver can withstand very little anti-burning power, generally around 10-20dBm. Therefore, there are two main situations that can cause receiver damage. One is that the external interference signal with large power is directly received by the antenna and enters the receiver. If there is no protection measure in the front stage of the receiver, the large interference signal will burn the low noise amplifier in the receiver, thereby causing damage to the receiver. Another situation is that when a circulator is used as a duplex device in the transceiver component, due to the limited isolation of the circulator, when the antenna transmits too much, the power of the transmitter's high-power signal leaking to the receiver channel is too large, causing damage to the receiver. In order to protect power-sensitive devices such as low noise amplifiers, a limiter is usually added in front of these devices for protection. Summary of the invention

[0003] The purpose of the present application is to provide a limiting circuit. The limiting circuit provided by the present application is conducive to optimizing the traditional limiter circuit, thereby providing a basis for obtaining a low-cost, high-performance limiting circuit and its integrated components.

[0004] In order to solve the above technical problems, the present application discloses a limiting circuit, comprising: a signal input end, a signal output end, at least one switch tube and at least one control unit;

[0005] The at least one control unit is used to control the on and off of the at least one switch tube;

[0006] The at least one switch tube is used to weaken the power of the radio frequency signal received by the signal input end in the on state and then output it through the signal output end.

[0007] The limiting circuit disclosed in the present application adopts a power detector to control the on and off of the FET to reduce the signal power at the signal receiving end. Compared with the traditional PIN diode-based structure, the limiting circuit disclosed in the present application can be implemented through traditional silicon technology, so it is low-cost and suitable for large-scale mass production; because the input and output of the signal in the limiting circuit disclosed in the present application do not require DC blocking capacitors, the limiting circuit has excellent ESD performance; because the switching tubes in the limiting circuit disclosed in the present application can be connected in series or in parallel, the limiting circuit occupies a small chip area and can be used to manufacture small-sized limiting devices; at the same time, because the switching tube can maintain a small capacitance in the disconnected state, the limiting circuit based on the present application has a small insertion loss, a large bandwidth but a large power capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 According to some embodiments of the present application, a circuit diagram of a limiting circuit is disclosed;

[0009] Figure 2 According to some embodiments of the present application, a circuit diagram of a limiter circuit using an NMOS transistor as a switch tube is disclosed;

[0010] Figure 3 According to some embodiments of the present application, a circuit diagram of a limiter circuit using a high resistance device and a voltage source to provide a control voltage is disclosed;

[0011] Figure 4 According to some embodiments of the present application, a circuit diagram of a limiter circuit using a switch and a voltage source to provide a control voltage is disclosed;

[0012] Figure 5 According to some embodiments of the present application, a circuit diagram of a limiter circuit using a power detector to provide a control voltage is disclosed;

[0013] Figure 6 According to some embodiments of the present application, a circuit diagram of a limiter circuit using a diode and a resistor as a power detector is disclosed;

[0014] Figure 7 According to some embodiments of the present application, a circuit diagram of a limiter circuit using a coupler and a diode as a power detector is disclosed;

[0015] Figure 8 According to some embodiments of the present application, a circuit diagram of a limiter circuit using an amplifier to amplify a control signal is disclosed;

[0016] Fig. 9 According to some embodiments of the present application, a circuit diagram of a limiter circuit using switch tubes connected in series is disclosed;

[0017] Fig.10 According to some embodiments of the present application, a circuit diagram of a limiter circuit using switches connected in series is disclosed;

[0018] Fig.11 According to some embodiments of the present application, a circuit diagram of a limiting circuit using a plurality of switch tubes connected in parallel is disclosed;

[0019] Fig.12 According to some embodiments of the present application, a circuit diagram of a limiting circuit using two switch tube sets connected in parallel is disclosed;

[0020] Fig.13 According to some embodiments of the present application, a chip structure example diagram of a limiting circuit based on the present disclosure is disclosed;

[0021] Fig.14 According to some embodiments of the present application, a schematic diagram of chip assembly based on the limiting circuit of the present disclosure is disclosed;

[0022] Fig.15 According to some embodiments of the present application, a limiting characteristic test diagram based on the limiting circuit of the present disclosure is disclosed. DETAILED DESCRIPTION

[0023] Illustrative embodiments of the present application include, but are not limited to, a clipping circuit.

[0024] The present application will use the terms commonly used by those skilled in the art to describe the various aspects of the illustrative embodiments, so that the essence of their work is conveyed to other technicians in the field. However, it is obvious to those skilled in the art that some alternative embodiments can be put into practice using parts of the described aspects. For the purpose of explanation, in order to provide a thorough understanding of the illustrative embodiments, specific numbers, materials and configurations are described. However, it is obvious to those skilled in the art that alternative embodiments can be implemented without specific details. In other cases, in order not to confuse the illustrative embodiments, some well-known features are omitted or simplified.

[0025] In order to make the objectives, technical solutions and advantages of the present application more clear, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0026] According to an embodiment of the present application, a limiting circuit is disclosed. Figure 1 is the circuit diagram of the limiting circuit. Specifically, Figure 1As shown, the RF signal enters the limiting circuit from the input end and is output from the output end. The actual function of the switch tube in the circuit can be equivalent to the switch 103 connected between the input end 101 and the output end 102 in the figure, and the on and off of the switch is controlled by the control voltage provided by the control unit 104. When the control voltage provided by the control unit 104 is small, the switch 103 is disconnected and presents a high-resistance state, which basically does not affect the transmission of the signal. When the control voltage provided by the control unit 104 exceeds the preset threshold, the switch 103 is turned on and presents a low-resistance state, which is equivalent to a small resistor connected in parallel to the ground, and the resistance of the resistor decreases with the increase of the control voltage provided by the control unit 104. The RF signal passes through the resistor to the ground, which greatly reduces the output signal power. Therefore, when the control voltage provided by the control unit 104 is large enough, the output signal power can be limited to a safe range.

[0027] In some embodiments, the switch tube can be implemented by a field effect transistor (FET), specifically including a junction field effect transistor, a junction field effect transistor (JFET), a high electron mobility transistor (HEMT), a metal semiconductor field effect transistor (MESFET), a metal-oxide semiconductor field effect transistor (MOSFET), etc.

[0028] In some embodiments, the switch is implemented by using an N-type field effect transistor (N Metal-Oxide-Semiconductor Field-Effect Transistor, NMOS FET) or a P-type field effect transistor (P Metal-Oxide-SemiconductorField-Effect Transistor, PMOS FET). Figure 2The figure shows a specific embodiment implemented by NMOS. When the control voltage provided by the control unit 204 is less than the threshold voltage of the switch tube 203, the switch tube 203 is in the disconnected state, which is equivalent to a high-resistance state. At this time, no current flows, so the RF signal can pass through with low insertion loss. When the control voltage provided by the control unit 204 is greater than the threshold voltage of the switch tube 203, the switch tube 203 is in the on state, which is equivalent to a low-resistance state, and the impedance of the switch tube 203 decreases as the control voltage provided by the control unit 204 increases, which is equivalent to a voltage-controlled current source. When the control voltage provided by the control unit 204 is large enough, the switch tube 203 is fully turned on and located in the triode region, and the on-resistance is small enough, so that most of the RF signal passes through the resistor to the ground, thereby achieving a limiting effect.

[0029] In addition, it can be understood that in other embodiments, the switch tube can also be implemented by other transistors, which is not limited here.

[0030] In some embodiments, the control unit of the switch tube in the circuit is provided in a variety of ways. Figure 3 As shown, the high resistance device 304 (which can be a resistor, an inductor or a combination of the two) is connected between the first electrode of the switch tube 303 and the voltage source 305. In practical applications, the impedance of the high resistance device 304 is generally much larger than the impedance of the parasitic capacitance between nodes ① and ②, and the impedance of the parasitic capacitance between nodes ① and ③, so that the voltage amplitude of node ① is proportional to the voltage amplitude of node ②. At the same time, the impedance of the high resistance device 304 is large enough to prevent the RF signal from leaking through the high resistance device 304. As shown in the attached figure, Figure 4 As shown, the switch 404 is connected between the first electrode of the switch tube 403 and the voltage source 405. When the switch 404 is in the on state, the voltage of the voltage source 405 is transmitted to the first electrode of the switch tube 403, and then the switch 404 is disconnected, so that the voltage of the first electrode of the switch tube 403 can be maintained. In addition, it can be understood that in other embodiments, the control unit can also use other methods to control the on and off of the switch tube, which is not limited here.

[0031] In some embodiments, the voltage source can be Figure 5The power detector 505 shown is replaced. One end of the power detector 505 is connected to the input end 101 of the RF signal, and the other end is connected to the switch tube 503 through the high resistance device 504. The power detector 505 can detect the power of the RF signal input from the input end 101, and generate a corresponding DC voltage to control the on and off of the switch tube 503. When the input RF signal power is small, the DC voltage output by the power detector 505 is 0 or the output DC voltage is very small. The output voltage is not enough to turn on the switch tube 503, which is equivalent to a high resistance state, so the RF signal can pass through with low insertion loss. When the input RF signal power is large enough, the DC voltage output by the power detector 505 exceeds the threshold of the switch tube 503, so that the switch tube 503 is in the on state and the on resistance is small enough. At this time, most of the input RF signal passes through the resistor to the ground, so the signal power reaching the output end 102 is reduced. The advantage of using the power detector 505 is that the control voltage provided by the control unit changes with the change of the input RF signal power. The entire limiter circuit can monitor the power of the input RF signal in real time, and put the switch tube 503 in a high-resistance or low-resistance state according to the power of the input RF signal, thereby achieving the purpose of limiting. The entire process does not require manual setting of the control voltage value provided by the control unit.

[0032] In some embodiments, the power detector can be implemented in a variety of ways. Figure 6 As shown, the power detector 605 is composed of a diode 606 and a resistor 607. The anode of the diode 606 is connected to the input terminal 101, and the cathode of the diode 606 is connected to one end of the high resistance device 604. One end of the resistor 607 is connected to the cathode of the diode 606, and the other end is grounded. When the power of the RF signal inputted from the input terminal 101 is small, it is not enough to turn on the diode 606, and the diode 606 is in a high resistance state. The corresponding control voltage of the control switch tube 603 is very small, which is not enough to turn on the switch tube 603, so the RF signal can pass through with low insertion loss. When the power of the input RF signal is large, the diode 606 starts to turn on and rectifies the input RF signal to generate a DC signal, which increases as the input RF power increases. When the power of the input RF signal is large enough, the DC signal generated by the diode 606 is sufficient to turn on the switch tube 603, and the on-resistance is small enough. At this time, most of the RF signal passes through the resistor 607 to the ground. However, the disadvantages of this structure are that the parasitic capacitance of the diode 606 will affect the insertion loss of the limiting circuit, and the diode 606 is directly connected to the input terminal 101. When the power of the input RF signal is very large, the diode 606 is easy to burn out. Figure 7 FIG. 7 is a power detector 705 of an improved structure, which includes a diode 706, a resistor 707 and a power coupler 708. The power coupler 708 is arranged near the input terminal 101, and the coupling amount is determined according to the characteristics of the selected diode 706. The role of the diode 706 is similar to that of the attached Figure 6 The diode 606 has the same function, and the coupling amount of the power coupler 708 is appropriate, which has little effect on the insertion loss of the limiting circuit. At the same time, because the signal power coupled by the power coupler 708 is much smaller than the power of the input section 101, the diode 706 is not easily burned due to excessive current. Figure 7 The disadvantage of the structure is that the power coupled from the power coupler 708 to the diode 706 is often small, and it is difficult for the diode 706 to detect a large DC signal to turn on the switch tube 703. Figure 8 Another improved structure of the power detector 805 is shown. Based on the structure of the power detector 705, an amplifier 809 is connected between the diode 806 and the high-resistance device 804. The functions of the amplifier 809 are: first, to amplify the DC signal detected by the diode 806 so that the switch tube 803 can be turned on as quickly as possible to achieve limiting, that is, to reduce the starting level of the limiting circuit; second, to enhance the driving capability to reduce the response recovery time.

[0033] In some embodiments, in certain specific processes, such as SOI process, high-resistance silicon process, multi-well CMOS process or gallium arsenide process, FETs are well isolated from each other, allowing FETs to be connected in series. In such a process, multiple switch tubes in the limiter circuit according to the present invention can also be connected in series. Taking two switch tubes in series as an example, the limiter circuit according to the present invention is as follows: Fig. 9 As shown. Among them, the second electrode of the switch tube 903 is connected to the input terminal 101, the third electrode is connected to the second electrode of the switch tube 905, and the third electrode of the switch tube 905 is grounded. Here, the on and off of the switch tube 903 is controlled by the control voltage provided by the control unit 904, and the on and off of the switch tube 905 is controlled by the control voltage provided by the control unit 906. The biggest advantage of connecting the switch tubes in series is that it can greatly increase the maximum power handling capacity of the limiting circuit. For example, if the maximum voltage that a single switch tube can withstand due to physical damage is Vmax, then if n switch tubes are connected in series, the maximum voltage that can withstand physical damage under ideal circumstances is increased to n×Vmax, so the maximum power handling capacity of the limiting circuit is also increased by n2 times. As shown in the attached Fig.10 FIG. 1 is another specific embodiment of the present invention, wherein the switch tube 1003 is connected in series with the switch tube 1005, the first electrode of the switch tube 1003 is connected to the resistor 1004, and the first electrode of the switch tube 1005 is connected to the resistor 1006. Here, the on and off of the switch tube 1003 and the switch tube 1005 are controlled by the control voltage provided by the control unit 1007.

[0034] In some embodiments, multiple switch tubes in the amplitude limiting circuit according to the present invention can also be connected in parallel, as shown in the attached Fig.11As shown, the switch tube 1103 is connected in parallel with the switch tube 1105, and the on-off of the switch tube 1103 is controlled by the control voltage provided by the control unit 1104, and the on-off of the switch tube 1105 is controlled by the control voltage provided by the control unit 1106. Similar to the above-mentioned limiter circuit including multiple switch tubes connected in series, when multiple switch tubes are connected in parallel, the on-off of each switch tube can be controlled separately by the control voltage provided by the respective control unit, or can be controlled together by the control voltage provided by the same control unit.

[0035] In some embodiments, multiple switch tube sets consisting of multiple switch tubes connected in series can also be connected in parallel with each other. The advantages of this structure are: first, the parasitic capacitance of a single switch tube can be distributed to multiple switch tube sets, which is easy to achieve distributed matching and improve bandwidth; second, in the design of multiple tube sets, the focus of consideration for each tube set can be different to achieve better performance. For example, the number of series connections of different tube sets can be different. A tube set with a large number of series connections can withstand greater power, but the response recovery time is longer. Although a tube set with a small number of series connections withstands less power, it can respond and recover quickly. In practical applications, a tube set with a large number of series connections and a tube set with a small number of series connections are used in parallel, which can respond quickly and withstand high power. As shown in the attached figure Fig.12 As shown, it is an example of a limiting circuit based on a switch tube that comprehensively applies the above-mentioned multiple technologies and structures. The limiting circuit mainly includes a radio frequency signal transmission line 1204 for transmitting radio frequency signals; a control unit 1203 for detecting the power of the radio frequency signal input from the input terminal 101, and then generating a corresponding control voltage to control the on and off of the first switch tube set 1201 and the second switch tube set 1202. The first switch tube set 1201 does not affect signal transmission when in the disconnected state, and limits the input signal when in the on state; the second switch tube set 1202 forms an LC filter with the first switch tube set and the radio frequency signal transmission line 1204 when in the disconnected state to ensure low-loss transmission of the input signal. When the second switch tube set 1202 is turned on, the input signal is further limited to reduce the limiting level.

[0036] In some embodiments, the input end of the control unit 1203 is connected to the input end of the RF signal transmission line 1204, and the output end is connected to the control end of the first switch tube set 1201 and the second switch tube set 1202, for controlling the on and off of the switch tubes in the tube set. One end of the first switch tube set 1201 is connected to the RF signal transmission line 1204, and the other end is grounded. One end of the second switch tube set 1202 is connected to the RF signal transmission line 1204, and the other end is grounded.

[0037] In some embodiments, the RF signal transmission line 1204 between the input end 101 and the output end 102 is mainly composed of four high-resistance microstrip lines 12041, 12042, 12043 and 12044, which are stacked with two layers of thick metal in the silicon process, and have large width and thickness to withstand high RF power. The input and output of the transmission line have pads for bonding gold wires, and the pad size is 100um×100um. The small signal S parameters of the limiter circuit can be optimized by adjusting the width and length of the microstrip lines 12041, 12042, 12043 and 12044 to meet the design requirements.

[0038] In some embodiments, the control unit 1203 mainly includes a detector diode 12031, a resistor 12032, and a control port 12033. The positive electrode of the detector diode 12031 is connected to the input end of the RF signal transmission line 1204, and the negative electrode is connected to the resistor 12032 and the control end of the switch tube set 1201, 1202. One end of the resistor 12032 is connected to the negative end of the detector diode, and the other end is grounded. The control port 12033 is led out from the control port of the switch tube set. When the input signal power is small, the detector diode 12031 is not turned on. When the input signal power is greater than a certain value, the detector diode 12031 is turned on, and the output voltage signal is used to control the conduction state of each switch tube, thereby achieving a limiting effect. When the input signal returns to a normal value, the detector diode 12031 is disconnected, and each switch tube discharges through the resistor 12032, so that the control end voltage drops, the switch tube is disconnected, and the output signal also returns to a normal value. In addition, the control port 12033 has two application modes. One is to control the on / off of the switch tube by external control signals. In this case, the internal high-power switch is controlled by the external control signal. The other application mode is to leave the control port unused. In this case, the internal power detector generates a control signal to control the on / off of the high-power switch.

[0039] In some embodiments, the first switch tube set includes switch tubes 12011, 12013, 12015, 12017, 12019 connected in series and resistors 12010, 12012, 12014, 12016, 12018 connected to the first electrodes of each switch tube, respectively. This series connection can withstand greater power. It should be understood that only 5 switch tubes are connected in series here for example, and the number of switch tubes connected in series in the switch tube set is not limited. The specific number needs to be selected according to the power size and small signal S parameter index requirements required in actual applications. The electrode-connected resistors 12010, 12012, 12014, 12016, 12018 are connected to the first electrodes of the corresponding switch tubes to isolate the radio frequency signal and reduce the insertion loss. In addition, the switch tubes 12011, 12013, 12015, 12017, 12019 are not required to be of the same size, and can be specifically designed according to the voltage distribution and index requirements. Similarly, the resistors 12010, 12012, 12014, 12016, and 12018 are not required to be of the same size. When the RF signal passes through the first switch tube set 1201, if the signal voltage amplitude is less than the conduction voltage of the detector diode 12031 in the control unit 1203, each switch tube in the switch tube set 1201 is in a disconnected state, which is equivalent to a capacitor connected in parallel to the ground, and the RF signal passes through; when the signal voltage amplitude is greater than the conduction voltage of the detector diode 12031 in the control unit 1203, each switch tube in the switch tube set 1201 is in a conducting state, which is equivalent to a small resistor connected in parallel to the ground, and the RF signal passes through the switch tube to the ground, which greatly reduces the output signal power.

[0040] In some embodiments, the second switch tube set 1202 includes switch tubes 12021, 12023, and 12025, and resistors 12020, 12022, and 12024 respectively connected to the first electrodes of each switch tube, and each switch tube is connected in the same series structure as each switch tube in the first switch tube set 1201. The number of switch tubes in the second switch tube set can be less than that in the first switch tube set, so that when the RF signal passes through the second switch tube set, because the number of series connections is small, it can respond quickly, eliminate power spikes, and further reduce the limiting level. It should be understood that here, only three switch tubes are connected in series for exemplary description, and the specific number of switch tubes in the second switch tube set is not limited.

[0041] The schematic diagram of the chip of the limiting circuit disclosed in this application is shown in the attached figure. Fig.13As shown. Preferably, the single chip is 950um long and 1650um wide. The figure shows the positions of the input terminal 1301 pressure point, the output terminal 1302 pressure point and the control terminal 1303 pressure point. At the same time, there are text markings on the single chip, among which RFin represents the input terminal interface of the RF signal, RFout identifies the output terminal interface of the RF signal, and VCTRL represents the control terminal interface. In addition, the control terminal 1303 has two application modes. One is that the control signal can be connected from the outside to control the on and off of the switch tube. At this time, the internal high-power switch is controlled by the external control signal. Another application mode is to leave the control port unused. At this time, the internal RF power detector generates a control signal to control the on and off of the high-power switch.

[0042] The chip assembly schematic diagram of the limiting circuit disclosed in this application is shown in the attached figure. Fig.14 As shown. The chip can be bonded with conductive glue, and the input end 1301 and the output end 1302 can be connected with gold wire and external microstrip line. Preferably, two gold wires can be used for connection, and the shorter the gold wire length, the better. The control end 1303 can be connected with gold wire and external microstrip line, or directly connected with gold wire and external control pin. It should be noted that during assembly, the input end of the limiter circuit must correspond to the transmission direction of the signal.

[0043] In some embodiments, Fig.15 The figure shows the relationship curve between the input power Pin and the output power Pout when a continuous wave power signal is input into the limiting circuit according to the present invention under normal temperature. The overall curve can be divided into two regions: A, linear region. In this region, the input signal power Pin is small, the output signal power Pout is almost the same as the input signal power Pin, and the signal passes through almost without attenuation; B, limiting region. In this region, when the input signal power Pin is higher than the threshold level, that is, higher than about 13dBm, the output signal power Pout begins to attenuate, and then as the input signal power Pin increases, the output signal power Pout is basically within the designed safety range. It can be seen from the test results that when the input signal power Pin is less than or equal to 43dBm, the maximum leakage level of the limiting circuit disclosed in the present application is less than 15dBm.

[0044] In some embodiments, the wireless receiving device disclosed in the present application includes the limiting circuit in the above-mentioned embodiments. The structure of the wireless receiving device can adopt the wireless receiving device commonly used in the prior art that can limit the input radio frequency signal, and mainly includes the front end of the receiving device, a demodulator, a limiter, and a device housing. Among them, the limiter in the wireless receiving device reduces the power of the received radio frequency signal by using the limiting circuit disclosed in the present application, thereby avoiding the low noise amplifier in the receiver from being burned, thereby protecting the wireless signal receiver. It should be understood that here only the wireless receiving device including the limiting circuit disclosed in the present application is used as an example for explanation, and the specific structure and application environment of the wireless receiving device are not limited. The specific structure and parameters of the wireless receiving device can be selected and adjusted according to actual needs.

[0045] The present application also discloses some embodiments, specifically:

[0046] Embodiment 1 may include a limiting circuit, the circuit including: a signal input end, a signal output end, at least one switch tube and at least one control unit;

[0047] The at least one control unit is used to control the on and off of the at least one switch tube;

[0048] The at least one switch tube is used to weaken the power of the radio frequency signal received by the signal input end in the on state and then output it through the signal output end.

[0049] Embodiment 2 may include the circuit described in Embodiment 1, wherein the limiting circuit further includes at least one resistor corresponding to each of the at least one switching tube, the first electrode of the switching tube is connected to the first end of the corresponding resistor, and the second end of the resistor is connected to the control unit.

[0050] Embodiment 3 may include the circuit described in Embodiment 1 or 2, wherein the limiting circuit includes a switching tube, wherein the first electrode of the switching tube is connected to the control unit, the second electrode of the switching tube is connected to the signal input end and the signal output end, and the third electrode of the switching tube is grounded.

[0051] Embodiment 4 may include the circuit described in any one of embodiments 1 to 3, wherein the limiting circuit includes at least two switching tubes, and the at least two switching tubes are connected in parallel with each other.

[0052] Embodiment 5 may include the circuit described in any one of Embodiments 1 to 4, wherein the second electrodes of the at least two switch tubes are connected to the signal input end and the signal output end, and the third electrodes of the at least two switch tubes are grounded.

[0053] Embodiment 6 may include the circuit described in any one of Embodiments 1 to 5, wherein the first electrodes of the at least two switching tubes are respectively connected to two control units.

[0054] Embodiment 7 may include the circuit described in any one of Embodiments 1 to 5, wherein the first electrodes of the at least two switching tubes are connected to the same control unit.

[0055] Embodiment 8 may include the circuit described in any one of Embodiments 1 to 3, wherein the limiting circuit includes at least two switching tubes, and the at least two switching tubes are connected in series.

[0056] Embodiment 9 may include the circuit described in Embodiment 8, wherein the second electrode of the first switch tube among the at least two switch tubes is connected to the signal input end and the signal output end, and the third electrode of the second switch tube among the at least two switch tubes is grounded.

[0057] Embodiment 10 may include the circuit described in Embodiment 8 or 9, wherein the first electrodes of the at least two switching tubes are respectively connected to two control units.

[0058] Embodiment 11 may include the circuit described in Embodiment 8 or 9, wherein the first electrodes of the at least two switching tubes are connected to the same control unit.

[0059] Embodiment 12 may include the circuit described in any one of embodiments 1 to 11, wherein the amplitude limiting circuit includes a first switch tube set and a second switch tube set connected in parallel with each other;

[0060] The first switch tube set includes at least two switch tubes connected in series, and the second switch tube set includes at least two switch tubes connected in series.

[0061] Embodiment 13 may include the circuit described in any one of embodiments 1 to 12, wherein the second electrode of a switch tube in the first switch tube set is connected to the signal input end and the signal output end, and the third electrode is connected to the second electrode of the switch tube connected in series with the switch tube.

[0062] Embodiment 14 may include the circuit described in any one of embodiments 1 to 12, wherein the third electrode of a switch tube in the first switch tube set is grounded, and the second electrode is connected to the third electrode of the switch tube connected in series with the switch tube.

[0063] Embodiment 15 may include the circuit described in any one of embodiments 1 to 12, wherein the second electrode of a switch tube in the second switch tube set is connected to the signal input end and the signal output end, and the third electrode is connected to the second electrode of the switch tube connected in series with the switch tube.

[0064] Embodiment 16 may include the circuit described in any one of embodiments 1 to 12, wherein the third electrode of a switch tube in the second switch tube set is grounded, and the second electrode is connected to the third electrode of the switch tube connected in series with the switch tube.

[0065] Embodiment 17 may include the circuit described in any one of Embodiments 1 to 16, wherein first electrodes of different switch tubes included in the first switch tube set and the second switch tube set are connected to the same control unit.

[0066] Embodiment 18 may include the circuit described in any one of Embodiments 1 to 16, wherein first electrodes of different switch tubes included in the first switch tube set and the second switch tube set are connected to different control units.

[0067] Embodiment 19 may include the circuit of any one of embodiments 1 to 18, wherein the control unit is a voltage source.

[0068] Embodiment 20 may include the circuit of any one of embodiments 1 to 18, wherein the control unit is a power detector.

[0069] Embodiment 21 may include the circuit described in Embodiment 20, wherein the power detector is capable of generating a corresponding DC voltage to control the on and off of the switch tube according to the detected power of the signal input terminal.

[0070] Embodiment 22 may include the circuit described in any one of embodiments 1 to 21, wherein the switch tube is a field effect transistor.

[0071] Embodiment 23 may include a wireless receiving device, which includes the limiting circuit described in any one of Embodiments 1 to 22.

[0072] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes made within the knowledge scope of ordinary technicians in the field without departing from the purpose and spirit of the present invention should fall within the scope of the patent of the present invention.

[0073] In the accompanying drawings, some structural or method features may be shown in a specific arrangement and / or order. However, it should be understood that such a specific arrangement and / or order may not be required. Instead, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. In addition, the inclusion of structural or method features in a particular figure does not mean that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0074] It should be noted that, in the examples and description of the present invention, relational terms such as first and second, etc., are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise one" do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0075] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application.

Claims

1. A limiting circuit, characterized in that: include: A signal input terminal, a signal output terminal, at least one switch tube and at least one control unit; The at least one control unit provides a control voltage to the at least one switch tube, so as to control the on and off of the at least one switch tube; The at least one switch tube is used to weaken the power of the radio frequency signal received by the signal input terminal in the on state and then output it through the signal output terminal; Wherein, the at least one control unit comprises a diode and a resistor, the anode of the diode is connected to the signal input terminal, the cathode of the diode is grounded via the resistor, and the cathode of the diode is connected to the at least one switch tube via a high resistance device to provide a control voltage to the at least one switch tube; Alternatively, the at least one control unit includes a power coupler, a resistor and a diode, the power coupler is connected to the signal input end to couple power to the anode of the diode, and the anode of the diode is also grounded via the resistor, and the cathode of the diode is connected to the at least one switching tube via a high-resistance device to provide a control voltage to the at least one switching tube.

2. The circuit according to claim 1, characterized in that The amplitude limiting circuit also includes at least one resistor corresponding to each of the at least one switch tube, a first electrode of the switch tube is connected to a first end of the corresponding resistor, and a second end of the resistor is connected to the control unit.

3. The circuit according to claim 1, characterized in that The limiting circuit includes a switch tube, wherein a first electrode of the switch tube is connected to the control unit, a second electrode of the switch tube is connected to the signal input end and the signal output end, and a third electrode of the switch tube is grounded.

4. The circuit according to claim 1, characterized in that The amplitude limiting circuit includes at least two switch tubes, and the at least two switch tubes are connected in parallel.

5. The circuit according to claim 4, characterized in that The second electrodes of the at least two switch tubes are connected to the signal input end and the signal output end, and the third electrodes of the at least two switch tubes are grounded.

6. The circuit according to claim 5, characterized in that The first electrodes of the at least two switching tubes are connected to two control units respectively.

7. The circuit according to claim 5, characterized in that The first electrodes of the at least two switch tubes are connected to the same control unit.

8. The circuit according to claim 1, characterized in that The amplitude limiting circuit includes at least two switch tubes, and the at least two switch tubes are connected in series.

9. The circuit according to claim 8, characterized in that The second electrode of the first switch tube among the at least two switch tubes is connected to the signal input end and the signal output end, and the third electrode of the second switch tube among the at least two switch tubes is grounded.

10. The circuit according to claim 9, characterized in that The first electrodes of the at least two switching tubes are connected to two control units respectively.

11. The circuit according to claim 9, characterized in that The first electrodes of the at least two switch tubes are connected to the same control unit.

12. The circuit according to claim 1, characterized in that The limiting circuit includes a first switch tube set and a second switch tube set connected in parallel with each other; The first switch tube set includes at least two switch tubes connected in series, and the second switch tube set includes at least two switch tubes connected in series.

13. The circuit according to claim 12, characterized in that The second electrode of a switch tube in the first switch tube set is connected to the signal input end and the signal output end, and the third electrode is connected to the second electrode of the switch tube connected in series with the switch tube.

14. The circuit according to claim 12, characterized in that A third electrode of a switch tube in the first switch tube set is grounded, and the second electrode is connected to the third electrode of a switch tube connected in series with the switch tube.

15. The circuit according to claim 12, characterized in that A second electrode of a switch tube in the second switch tube set is connected to the signal input end and the signal output end, and a third electrode is connected to a second electrode of a switch tube connected in series with the switch tube.

16. The circuit according to claim 12, characterized in that A third electrode of a switch tube in the second switch tube set is grounded, and the second electrode is connected to the third electrode of the switch tube connected in series with the switch tube.

17. The circuit according to claim 12, characterized in that First electrodes of different switch tubes included in the first switch tube set and the second switch tube set are connected to the same control unit.

18. The circuit according to claim 12, characterized in that First electrodes of different switch tubes included in the first switch tube set and the second switch tube set are connected to different control units.

19. The circuit according to claim 1, characterized in that The at least one control unit includes the power coupler, the diode, the resistor and the amplifier. The power coupler is connected to the signal input end to couple power to the anode of the diode, and the anode of the diode is also grounded via the resistor. The cathode of the diode is connected to the at least one switching tube via a high-resistance device to provide a control voltage to the at least one switching tube. The amplifier is connected between the diode and the high-resistance device.

20. The circuit according to claim 1, characterized in that The switch tube is a field effect transistor.

21. A wireless receiving device, characterized in that: The invention comprises the limiting circuit according to any one of claims 1 to 20.

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