RF receiving circuit, receiver and base station

Abstract

The present invention relates to a radio frequency receiving circuit, a receiver and a base station. The radio frequency receiving circuit includes a duplexer, an integrated limiter, a low noise amplifier, a bandpass filter and a transceiver unit. The common port of the duplexer is used to electrically connect to the base station antenna. The duplexer, the integrated limiter, the low noise amplifier, the bandpass filter and the transceiver unit are cascaded in sequence. Among them, the integrated limiter is used to limit the same-frequency large signal in the received signal output by the duplexer; the signal amplitude of the same-frequency large signal after limiting is lower than the saturation threshold of the low noise amplifier. Through the above-mentioned link structure design, the integrated limiter is used to limit the same-frequency large signal, so that after the same-frequency large signal is limited, its signal amplitude is lower than the saturation threshold of the low noise amplifier, effectively avoiding causing the low noise amplifier to saturate; at the same time, the insertion loss introduced by the integrated limiter is small and will not affect the useful signal in the small-amplitude signal, thereby achieving the purpose of avoiding damage to the receiver performance.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a radio frequency receiving circuit, a receiver and a base station. Background Art

[0002] With the development of mobile communication technology, the communication environment has become more complex, the types of signals in space have become more diverse, and the performance requirements for base station receivers have become more stringent. On the base station receiver, if a large-amplitude signal directly enters the receiver, there is a chance that the receiver's hardware link will be damaged. If the receiver's hardware link is partially damaged, the base station will not work properly, seriously affecting the user communication in the area covered by the base station, and the subsequent maintenance of the base station will also generate a lot of maintenance costs. Therefore, it is very important to protect the hardware link of the base station receiver.

[0003] In a communication system where the terminal is close to the base station, the transmitting frequency of the terminal happens to be the receiving frequency of the base station. Therefore, co-frequency interference will occur when the terminal and the base station work at the same time. The isolation of the base station antenna is limited, and the large interference signal of the same frequency will damage the electronic components in the hardware link of the receiver. The traditional receiver protection method is to design a special limiting protection circuit to limit all input signals. However, in the process of implementing the present invention, the inventor found that the traditional receiver protection method has the problem of impaired receiver performance for communication systems where the terminal is close to the base station. Summary of the invention

[0004] Based on this, it is necessary to provide a radio frequency receiving circuit, a receiver and a base station device that can effectively prevent the performance of the receiver from being damaged in order to address the problems existing in the above-mentioned traditional receiver protection methods.

[0005] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] On the one hand, an embodiment of the present invention provides a radio frequency receiving circuit, including a duplexer, an integrated limiter, a low noise amplifier, a bandpass filter and a transceiver unit;

[0007] The common port of the duplexer is used to electrically connect to the base station antenna, and the duplexer, the integrated limiter, the low noise amplifier, the band pass filter and the transceiver unit are sequentially cascaded;

[0008] The integrated limiter is used to limit the same-frequency large signal in the received signal output by the duplexer; the signal amplitude of the same-frequency large signal after limiting is lower than the saturation threshold of the low-noise amplifier.

[0009] In one of the embodiments, the radio frequency receiving circuit further includes an adjustable gain control unit, and the low noise amplifier is connected to the band pass filter via the adjustable gain control unit;

[0010] The adjustable gain control unit is used to perform gain adjustment on a small-amplitude signal in a received signal output by a low-noise amplifier; the power of the small-amplitude signal after gain adjustment is lower than an ADC overflow threshold of the transceiver unit.

[0011] In one embodiment, the adjustable gain control unit includes a controller and a controllable gain circuit, and the low noise amplifier is connected to the band pass filter through the controllable gain circuit;

[0012] The control output terminal of the controller is electrically connected to the gain control terminal of the controllable gain circuit, the power supply terminal of the controller is used to electrically connect to the power supply, and the controller is used to adjust the output gain of the controllable gain circuit;

[0013] The controllable gain circuit is used for detecting the power of the small amplitude signal output by the low noise amplifier and outputting it to the controller, and adjusting the power of the small amplitude signal.

[0014] In one of the embodiments, the adjustable gain control unit includes a detection circuit, a controller and a controllable gain circuit;

[0015] The detection circuit is cascaded with the controllable gain circuit, and the low noise amplifier is connected to the band pass filter through the detection circuit and the controllable gain circuit;

[0016] The power supply end of the controller is used to electrically connect to the power supply, the detection input end of the controller is electrically connected to the detection output end of the detection circuit, and the control output end of the controller is electrically connected to the gain control end of the controllable gain circuit;

[0017] The detection circuit is used to detect the power of the small amplitude signal output by the low noise amplifier and output it to the controller. The controller is used to adjust the output gain of the controllable gain circuit. The controllable gain circuit is used to adjust the power of the small amplitude signal.

[0018] In one embodiment, the controller includes an FPGA chip, a CPLD device or a single-chip microcomputer.

[0019] In one embodiment, the controllable gain circuit includes an adjustable gain amplifier or an adjustable power attenuator.

[0020] In one of the embodiments, the transceiver unit is further used to perform gain adjustment on the small-amplitude signal in the received signal output by the bandpass filter; the power of the small-amplitude signal after gain adjustment is lower than the ADC overflow threshold of the transceiver unit.

[0021] On the other hand, a receiver is also provided, comprising the above-mentioned radio frequency receiving circuit.

[0022] On the other hand, a base station is provided, comprising a base station antenna and the above-mentioned receiver.

[0023] In one embodiment, the base station is a NB-IOT base station.

[0024] One of the above technical solutions has the following advantages and beneficial effects:

[0025] The above-mentioned RF receiving circuit, receiver and base station are designed with a link structure of a duplexer, an integrated limiter, a low-noise amplifier, a bandpass filter and a transceiver unit. The receiving signal output by the base station antenna enters the RF receiving circuit through the duplexer. When the received signal contains a large-amplitude large signal of the same frequency, the integrated limiter will limit the large signal of the same frequency, so that after the large signal of the same frequency is limited, its signal amplitude is lower than the saturation threshold of the low-noise amplifier. In this way, when the large signal of the same frequency sent by the terminal is received, the low-noise amplifier can be effectively avoided from being saturated by limiting the amplitude through the integrated limiter, thereby achieving the effect of protecting the low-noise amplifier and avoiding the overflow of the ADC (analog-to-digital converter) of the subsequent transceiver unit. At the same time, the insertion loss introduced by the integrated limiter is small and the integrated limiter does not limit the small-amplitude signal, so that the useful signal in the small-amplitude signal in the received signal is not affected, thereby achieving the purpose of avoiding damage to the receiver performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a first structural schematic diagram of a radio frequency receiving circuit in an embodiment;

[0027] Figure 2 A schematic diagram of a limiting performance curve of an integrated limiter in one embodiment;

[0028] Figure 3 is a second structural schematic diagram of a radio frequency receiving circuit in one embodiment;

[0029] Figure 4 is a third structural schematic diagram of a radio frequency receiving circuit in one embodiment;

[0030] Figure 5 is a fourth structural schematic diagram of a radio frequency receiving circuit in one embodiment;

[0031] Figure 6 FIG. 4 is a schematic diagram of an application of a base station in an embodiment. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to another element and combined with it as a whole, or there may be a centering element at the same time, that is, it may also be indirectly connected to another element.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] See also Figure 1 and Figure 2 , an embodiment of the present invention provides a radio frequency receiving circuit 100, including a duplexer 12, an integrated limiter 14, a low noise amplifier 16, a bandpass filter 18 and a transceiver unit 19. The common port of the duplexer 12 is used to electrically connect to the base station antenna 101. The duplexer 12, the integrated limiter 14, the low noise amplifier 16, the bandpass filter 18 and the transceiver unit 19 are cascaded in sequence. Among them, the integrated limiter 14 is used to limit the same-frequency large signal in the received signal output by the duplexer 12. The signal amplitude of the same-frequency large signal after limiting is lower than the saturation threshold of the low noise amplifier 16.

[0035] It can be understood that the duplexer 12 refers to a duplexer 12 commonly used in the art, and is used to realize that the RF receiving circuit and the RF transmitting circuit of the base station are respectively connected to the base station antenna 101. The integrated limiter 14 can be various types of integrated limiting chips available on the market, and the specific type can be determined according to the signal limiting capability required to protect the low-noise amplifier 16 in the actual application scenario, as long as the level of the output signal after limiting does not cause the saturation of the low-noise amplifier 16. The low-noise amplifier 16 refers to a low-noise amplifier 16 used in the RF receiving link of the base station in a communication system where the terminal and the base station coexist, and is used to amplify the received signal output by the integrated limiter 14. The low-noise amplifier 16 can be various types of traditional low-noise amplifiers 16, which can be specifically determined by the type of low-noise amplifier 16 specifically used in the RF receiving link of the base station in the actual application scenario.

[0036] The bandpass filter 18 and the transceiver unit 19 are both link devices used in the RF receiving link of the base station in the communication system where the terminal and the base station coexist. The bandpass filter 18 is used to provide the post-stage filtering function of the low-noise amplifier 16, and the transceiver unit 19 is used to provide the functions of receiving and processing the uplink / downlink signals of the base station and sending and processing. For details, please refer to the use of the transceiver unit 19 in the hardware link of the receiver of the traditional base station. The saturation threshold refers to the signal amplitude threshold that causes the low-noise amplifier 16 to enter the saturation state from the normal working state. Among them, Figure 1 TX in the figure represents the transmitter output port of the base station.

[0037] Specifically, in actual application scenarios, the distance between the terminal and the base station is relatively close, forming a communication system in which the terminal and the base station coexist. When the terminal and the base station are working at the same time, the base station can just receive the terminal's transmission signal at the same frequency. Since the isolation provided by the base station antenna 101 is limited, the terminal's transmission signal will be received by the base station antenna 101, and a large co-frequency signal with a large signal amplitude will be formed. When the received signal entering through the base station antenna 101 is a large co-frequency signal sent by the terminal, if the signal amplitude of the large co-frequency signal exceeds the low-noise saturation threshold, the large co-frequency signal will directly enter the low-noise amplifier 16 after being output from the duplexer 12, which will cause the low-noise amplifier 16 to enter a saturated state and damage the low-noise amplifier 16.

[0038] An integrated limiter 14 selected according to the saturation threshold of the low noise amplifier 16 is connected between the duplexer 12 and the low noise amplifier 16. When the received signal is mainly a large signal of the same frequency, the integrated limiter 14 can limit the large signal of the same frequency with a large signal amplitude, and limit the signal amplitude of the large signal of the same frequency to below the saturation threshold of the low noise amplifier 16, so as to avoid saturation of the low noise amplifier 16 when the received signal enters the low noise amplifier 16 for amplification. The received signals in different time periods will be different. By selecting the integrated limiter 14, it is only necessary to limit the large signal of the same frequency, and when a small-amplitude signal is input, the integrated limiter 14 will not limit the small-amplitude signal, so as not to affect the useful signal contained in the small-amplitude signal. Figure 2 The figure shows the limiting performance curve of one of the integrated limiters 14 in actual application. By using this type of integrated limiter 14 or one with similar output performance, the limiting processing of large signals with the same frequency can be effectively realized without limiting the effect of small signals. The two curves 005 and 007 respectively represent two different limiting performances.

[0039] The radio frequency receiving circuit 100 is designed with a link structure of a duplexer 12, an integrated limiter 14, a low noise amplifier 16, a bandpass filter 18 and a transceiver unit 19. The received signal output by the base station antenna 101 enters the radio frequency receiving circuit 100 through the duplexer 12. When the received signal contains a large-amplitude co-frequency large signal, the integrated limiter 14 will limit the co-frequency large signal so that the signal amplitude of the co-frequency large signal is lower than the saturation threshold of the low noise amplifier 16 after limiting. In this way, when the co-frequency large signal sent by the terminal is received, the integrated limiter 14 is used to limit the signal, which can effectively avoid saturation of the low noise amplifier 16, thereby achieving the effect of protecting the low noise amplifier 16 and avoiding overflow of the ADC (analog-to-digital converter) of the subsequent transceiver unit 19. At the same time, the insertion loss introduced by the integrated limiter 14 is small and the integrated limiter 14 does not limit the small-amplitude signal, so that the useful signal in the small-amplitude signal in the received signal is not affected, thereby achieving the purpose of avoiding damage to the receiver performance.

[0040] In one embodiment, the transceiver unit 19 is further used to perform gain adjustment on the small-amplitude signal in the received signal output by the bandpass filter 18. The power of the small-amplitude signal after gain adjustment is lower than the ADC overflow threshold of the transceiver unit 19.

[0041] It can be understood that the ADC overflow threshold is the overflow power threshold of the ADC (Analog-to-Digital Converter) inside the real-time transceiver unit 19. When the signal power of the received signal input to the transceiver unit 19 exceeds the ADC overflow threshold, the ADC of the transceiver unit 19 will overflow, thereby damaging the internal circuits of the transceiver unit 19, such as filters, mixers, and ADC devices, etc., resulting in damage to the RF receiving circuit 100. In this field, the transceiver unit 19 of the base station is an integrated on-chip system, which integrates multiple processing units, such as but not limited to baseband processing units, mixing units, and filtering units. The specific type can be determined according to the specific type of the transceiver unit 19 actually equipped in the receiver of the base station in actual applications.

[0042] The transceiver unit 19 can usually be pre-configured, for example, by enabling the automatic gain control (AGC) function of the transceiver unit 19, so that for the small-amplitude signal entering the transceiver unit 19, the transceiver unit 19 can automatically adjust the gain through its own compatible automatic gain control function, thereby ensuring that the ADC module inside the transceiver unit 19 does not overflow. Specifically, in this embodiment, the uplink automatic gain control function compatible with the transceiver unit 19 can also be used to automatically detect the signal power of the small-amplitude signal output by the bandpass filter 18, and automatically adjust the link gain inside the transceiver unit 19 based on the detected signal power, such as backing off the link gain, so that the power of the small-amplitude signal with a signal power higher than the ADC overflow threshold is attenuated to below the ADC overflow threshold.

[0043] In this way, the transceiver unit 19 uses the above-mentioned automatic gain control function to adjust the gain of the small-amplitude signal when the signal power of the small-amplitude signal is too high, so as to attenuate the signal power of the small-amplitude signal, and ensure that when the small-amplitude signal enters the filter, mixer, ADC and other devices inside the transceiver unit 19, the signal power is within the power range allowed by each device, avoiding ADC overflow to ensure the blocking performance of the transceiver unit 19, thereby further protecting the device safety of the RF receiving circuit 100 and further avoiding damage to the receiver performance.

[0044] See also Figure 3In one embodiment, the RF receiving circuit 100 further includes an adjustable gain control unit 17. The low noise amplifier 16 is connected to the bandpass filter 18 via the adjustable gain control unit 17. The adjustable gain control unit 17 is used to perform gain adjustment on the small amplitude signal in the received signal output by the low noise amplifier 16. The power of the small amplitude signal after gain adjustment is lower than the ADC overflow threshold of the transceiver unit 19.

[0045] It can be understood that the adjustable gain control unit 17 refers to a signal gain circuit or signal attenuation circuit with controllable output gain, which can be various types of gain adjustable devices or circuit modules commonly used in radio frequency links in the field. The adjustable gain control unit 17 can directly sample the output signal from the output end of the low noise amplifier 16 to obtain the signal power of the received signal output by the low noise amplifier 16; the adjustable gain control unit 17 can also obtain the signal power of the received signal entering the transceiver unit 19 by receiving the signal power output by the transceiver unit 19, for example, the transceiver unit 19 obtains the signal power of the input signal through the internal integrated signal detection function and outputs it to the adjustable gain control unit 17. The adjustable gain control unit 17 can also obtain the signal power of the received signal output by the low noise amplifier 16 by receiving the output power of an externally separately set signal sampling device (such as a signal sampler additionally set on the receiver of the base station). The specific implementation method of the adjustable gain control unit 17 obtaining the signal power of the received signal of the post-stage of the low noise amplifier 16 can be determined according to the specific type of the adjustable gain control unit 17 or the specific type of the receiver used in the actual application scenario.

[0046] Specifically, in this embodiment, an adjustable gain control unit 17 is connected between the low noise amplifier 16 and the bandpass filter 18, and the adjustable gain control unit 17 performs gain adjustment on the small amplitude signal output by the low noise amplifier 16. When the signal power of the small amplitude signal after passing through the low noise amplifier 16 still exceeds the ADC overflow threshold of the transceiver unit 19, the adjustable gain control unit 17 automatically backs off the gain, so that the power of the small amplitude signal with a signal power higher than the ADC overflow threshold is attenuated to below the ADC overflow threshold. The way in which the adjustable gain control unit 17 automatically adjusts the gain can be understood in the same way as the various gain adjustment methods commonly used in the art.

[0047] In this way, the gain of the small-amplitude signal after passing through the low-noise amplifier 16 is automatically adjusted through the adjustable gain control unit 17, so that when the signal power of the small-amplitude signal is too high, the signal power of the small-amplitude signal is attenuated, ensuring that after the small-amplitude signal enters the transceiver unit 19, the signal power of the small signal is within the power range allowed by each device in the internal link of the transceiver unit 19, avoiding ADC overflow and thus ensuring the blocking performance of the transceiver unit 19, thereby further protecting the device safety of the RF receiving circuit 100 and further avoiding damage to the receiver performance.

[0048] See also Figure 4 In one embodiment, the adjustable gain control unit 17 includes a controller 172 and a controllable gain circuit 174. The low noise amplifier 16 is connected to the bandpass filter 18 through the controllable gain circuit 174. The control output end of the controller 172 is electrically connected to the gain control end of the controllable gain circuit 174. The power supply end of the controller 172 is used to electrically connect to a power supply. The controller 172 is used to adjust the output gain of the controllable gain circuit 174. The controllable gain circuit 174 is used to detect the power of the small amplitude signal output by the low noise amplifier 16 and output it to the controller 172, and adjust the power of the small amplitude signal.

[0049] It can be understood that the controller 172 can be a gain adjustment control circuit already existing in the art, or a separately set gain controller 172 or a main controller 172 of the receiver, which can be determined specifically according to the base station structure type or application cost of the actual application. The functions such as signal power comparison and gain adjustment instruction output implemented by the controller 172 can all be gain adjustment functions already existing in the art. The power supply refers to the power supply that provides the electrical energy required for the normal operation of the controller 172, which can be the power supply of the receiver or an independent power supply, such as but not limited to a rechargeable battery, a solar cell or a non-rechargeable battery. The specific type of the power supply can be determined according to the power supply requirements required by the controller 172 actually selected.

[0050] The controllable gain circuit 174 can be any type of controllable gain device with integrated signal power detection function in the art. While transmitting the received signal at a certain gain, the controllable gain circuit 174 can perform real-time sampling on the received signal passing through and output the sampled signal or signal power to the controller 172, so that the controller 172 can read the signal power of the sampled signal or directly receive the signal power to generate a corresponding gain control signal.

[0051] Specifically, during the operation of the base station, after the controller 172 is powered on, the signal power of the small-amplitude signal output by the low-noise amplifier 16 can be obtained in real time, and the obtained signal power is compared with the pre-stored ADC overflow threshold. When the signal power is greater than the ADC overflow threshold, a gain adjustment signal is output to the controllable gain circuit 174 to make the output gain of the controllable gain circuit 174 fall back. At this time, the signal power of the small-amplitude signal passing through the controllable gain circuit 174 will be attenuated to below the ADC overflow threshold of the transceiver unit 19 due to the output gain fallback of the controllable gain circuit 174, thereby ensuring that the small-amplitude signal that finally enters the transceiver unit 19 will not cause ADC overflow.

[0052] By setting the controller 172 and the controllable gain circuit 174 mentioned above, in coordination with the integrated limiter 14, the protection of the low noise amplifier 16 is achieved while more effectively protecting the link devices after the low noise amplifier 16, thereby ensuring the blocking performance of the applied receiver.

[0053] See also Figure 5 In one embodiment, the adjustable gain control unit 17 includes a detection circuit 171, a controller 172 and a controllable gain circuit 174. The detection circuit 171 is cascaded with the controllable gain circuit 174. The low noise amplifier 16 is connected to the bandpass filter 18 through the detection circuit 171 and the controllable gain circuit 174. The power supply end of the controller 172 is used to electrically connect to the power supply. The detection input end of the controller 172 is electrically connected to the detection output end of the detection circuit 171. The control output end of the controller 172 is electrically connected to the gain control end of the controllable gain circuit 174. The detection circuit 171 is used to detect the power of the small amplitude signal output by the low noise amplifier 16 and output it to the controller 172. The controller 172 is used to adjust the output gain of the controllable gain circuit 174. The controllable gain circuit 174 is used to adjust the power of the small amplitude signal.

[0054] It can be understood that the detection circuit 171 refers to a circuit for power sampling the received signal output by the low noise amplifier 16, and can be various types of signal power sampling devices commonly used in the art. Regarding the explanation of the controller 172 in this embodiment, the explanation of the controller 172 in the previous embodiment can be understood in the same way, and will not be repeated here. In this embodiment, the controllable gain circuit 174 can be various types of signal gain devices with controllable output gain that do not integrate a signal power detection function in the art.

[0055] Specifically, during the operation of the base station, after the controller 172 is powered on, the signal power of the small-amplitude signal output by the low-noise amplifier 16 can be obtained in real time through the detection circuit 171, and the obtained signal power is compared with the pre-stored ADC overflow threshold. When the signal power is greater than the ADC overflow threshold, a gain adjustment signal is output to the controllable gain circuit 174 to make the output gain of the controllable gain circuit 174 fall back. At this time, the signal power of the small-amplitude signal passing through the controllable gain circuit 174 will be attenuated to below the ADC overflow threshold of the transceiver unit 19 due to the output gain fallback of the controllable gain circuit 174, thereby ensuring that the small-amplitude signal that finally enters the transceiver unit 19 will not cause ADC overflow.

[0056] By setting up the above-mentioned detection circuit 171, controller 172 and controllable gain circuit 174, in coordination with the integrated limiter 14, the protection of the low noise amplifier 16 is achieved, and the link devices after the low noise amplifier 16 can also be more effectively protected to ensure the blocking performance of the applied receiver.

[0057] In one embodiment, the controller 172 includes an FPGA chip, a CPLD device, or a single-chip microcomputer. It is understood that an FPGA chip or a CPLD device can be used as the controller 172 for adjusting the output gain of the controllable gain circuit 174, wherein the FPGA chip or the CPLD device can be a chip or device for independent applications, or a chip or device for embedded applications, which can be determined according to the type of receiver in actual application, as long as the required gain adjustment function can be provided. In addition, a single-chip microcomputer can also be used as the controller 172 for adjusting the output gain of the controllable gain circuit 174, and the specific type can be selected according to the installation method and maintenance requirements of the actual application, as long as the required gain adjustment function can be provided.

[0058] By applying the above-mentioned FPGA chip, CPLD device or single-chip microcomputer, the output gain of the controllable gain circuit 174 can be adjusted. It can be directly purchased and connected to the link for use without additional development. The application cost is low and the reliability is high. It can effectively reduce the application and maintenance cost of the RF receiving circuit 100 and has high gain control efficiency.

[0059] In one embodiment, the controllable gain circuit 174 includes an adjustable gain amplifier or an adjustable power attenuator. It is understood that in this embodiment, the adjustable gain amplifier or adjustable power attenuator available in the art can be directly used to achieve power adjustment of the received signal output by the low noise amplifier 16. The adjustable gain amplifier or adjustable power attenuator is widely used in the art and has high reliability, which can effectively improve the reliability of the RF receiving circuit 100, thereby achieving power adjustment of small-amplitude signals while better reducing application costs and improving receiver performance.

[0060] In one embodiment, a receiver is further provided, comprising the above-mentioned radio frequency receiving circuit 100 .

[0061] It can be understood that, for the specific explanation of the RF receiving circuit 100 in this embodiment, reference can be made to the corresponding explanations in the above-mentioned embodiments of the RF receiving circuit 100, and no further description will be given here. It should be noted that those skilled in the art can understand that the RF receiving circuit 100 is a component of a receiver, and may actually include other components, such as but not limited to a filter or an additional power amplifier, etc., which may be determined according to the specific type of the receiver in actual application, and will not be described one by one in this specification.

[0062] The above receiver, by applying the above RF receiving circuit 100, after the base station antenna 101 receives the signal sent by the nearby terminal, inputs the received signal into the RF receiving circuit 100 through the duplexer 12. When the received signal contains a large-amplitude co-frequency large signal, the integrated limiter 14 in the RF receiving circuit 100 will limit the co-frequency large signal, so that after the co-frequency large signal is limited, its signal amplitude is lower than the saturation threshold of the low noise amplifier 16. In this way, when the co-frequency large signal sent by the terminal is received, the integrated limiter 14 is used for limiting, which can effectively avoid causing the saturation of the low noise amplifier 16, thereby achieving the effect of protecting the low noise amplifier 16 and avoiding causing the ADC (analog-to-digital converter) of the subsequent transceiver unit 19 to overflow. At the same time, the insertion loss introduced by the integrated limiter 14 is small and the integrated limiter 14 does not limit the small-amplitude signal, so that the useful signal in the small-amplitude signal in the received signal is not affected, thereby achieving the purpose of avoiding damage to the receiver performance.

[0063] See also Figure 6 In one embodiment, a base station 200 is also provided, comprising a base station antenna 101 and the above-mentioned receiver.

[0064] It can be understood that the explanation of the base station antenna 101 and the receiver in this embodiment can be understood by referring to the specific explanation of the base station antenna 101 and the receiver in the above corresponding embodiments, and will not be repeated in this embodiment and subsequent embodiments.

[0065] Specifically, in an actual application scenario, the distance between the terminal 301 and the base station 200 is relatively close, forming a communication system in which the terminal 301 and the base station 200 coexist. When the terminal 301 and the base station 200 work at the same time, the large co-frequency signal will interfere with the receiver RF link of the traditional base station, causing damage to the link components. By applying the above-mentioned new receiver, an integrated limiter 14 is connected between the duplexer 12 and the low-noise amplifier 16. When the received signal is mainly a large co-frequency signal, the integrated limiter 14 can be used to limit the large co-frequency signal with a large signal amplitude, and the signal amplitude of the large co-frequency signal is limited to below the saturation threshold of the low-noise amplifier 16, so as to avoid saturation of the low-noise amplifier 16 when the received signal enters the low-noise amplifier 16 for amplification.

[0066] The received signals in different time periods will be different. By selecting the integrated limiter 14, it is only necessary to limit the large signal of the same frequency. When a small-amplitude signal is input, the integrated limiter 14 will not limit the small-amplitude signal, thereby not affecting the useful signal contained in the small-amplitude signal.

[0067] The base station 200, by applying the new receiver, can limit the amplitude of the large signal of the same frequency sent by the terminal 301 through the integrated limiter 14, effectively avoiding saturation of the low noise amplifier 16, thereby protecting the low noise amplifier 16 and avoiding overflow of the ADC (analog-to-digital converter) of the subsequent transceiver unit 19. At the same time, the insertion loss introduced by the integrated limiter 14 is small and the integrated limiter 14 does not limit the small amplitude signal, so that the useful signal in the small amplitude signal in the received signal is not affected, thereby achieving the purpose of avoiding damage to the receiver performance.

[0068] In one embodiment, the base station 200 is a NB-IOT base station. It can be understood that in this embodiment, the base station 200 using the above-mentioned new receiver can be specifically a NB-IOT (i.e., narrowband Internet of Things) base station in the art, so as to better solve the signal interference of the uplink communication between each terminal 301 and the NB-IOT base station in the NB-IOT system, the problem of damage to the RF link of the receiver, realize the protection of the receiver hardware current, avoid the damage to the receiver performance, and better improve the service quality of the NB-IOT system.

[0069] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A radio frequency receiving circuit, characterized in that: Applicable to a communication system where a terminal and a base station coexist, including a duplexer, an integrated limiter, a low noise amplifier, a bandpass filter and a transceiver unit; wherein: When the terminal and the base station work simultaneously, the base station receives a large same-frequency signal formed by the transmission signal of the terminal at the same frequency point at the base station antenna; The common port of the duplexer is used to electrically connect to the base station antenna and output the same-frequency large signal to the integrated limiter; The duplexer, the integrated limiter, the low noise amplifier, the bandpass filter and the transceiver unit are cascaded in sequence; The integrated limiter is used to limit the same-frequency large signal in the received signal output by the duplexer to prevent the low-noise amplifier from saturating when the received signal output by the duplexer enters the low-noise amplifier for amplification; the signal amplitude of the same-frequency large signal after limiting is lower than the saturation threshold of the low-noise amplifier; the saturation threshold refers to the signal amplitude threshold that causes the low-noise amplifier to enter the saturation state from a normal working state.

2. The radio frequency receiving circuit according to claim 1, characterized in that: Also comprising an adjustable gain control unit, the low noise amplifier is connected to the band pass filter via the adjustable gain control unit; The adjustable gain control unit is used to perform gain adjustment on a small-amplitude signal in a received signal output by the low-noise amplifier; the power of the small-amplitude signal after gain adjustment is lower than an ADC overflow threshold of the transceiver unit.

3. The radio frequency receiving circuit according to claim 2, characterized in that: The adjustable gain control unit includes a controller and a controllable gain circuit, and the low noise amplifier is connected to the bandpass filter through the controllable gain circuit; The control output terminal of the controller is electrically connected to the gain control terminal of the controllable gain circuit, the power supply terminal of the controller is used to electrically connect to a power supply, and the controller is used to adjust the output gain of the controllable gain circuit; The controllable gain circuit is used for detecting the power of the small amplitude signal output by the low noise amplifier and outputting it to the controller, and adjusting the power of the small amplitude signal.

4. The radio frequency receiving circuit according to claim 2, characterized in that: The adjustable gain control unit includes a detection circuit, a controller and a controllable gain circuit; The detection circuit is cascaded with the controllable gain circuit, and the low noise amplifier is connected to the bandpass filter through the detection circuit and the controllable gain circuit; The power supply end of the controller is used to electrically connect to a power supply, the detection input end of the controller is electrically connected to the detection output end of the detection circuit, and the control output end of the controller is electrically connected to the gain control end of the controllable gain circuit; The detection circuit is used to detect the power of the small amplitude signal output by the low noise amplifier and output it to the controller. The controller is used to adjust the output gain of the controllable gain circuit. The controllable gain circuit is used to adjust the power of the small amplitude signal.

5. The radio frequency receiving circuit according to claim 3 or 4, characterized in that: The controller includes an FPGA chip, a CPLD device or a single-chip microcomputer.

6. The radio frequency receiving circuit according to claim 4, characterized in that: The controllable gain circuit includes an adjustable gain amplifier or an adjustable power attenuator.

7. The radio frequency receiving circuit according to claim 1, characterized in that: The transceiver unit is further used to perform gain adjustment on a small-amplitude signal in the received signal output by the bandpass filter; the power of the small-amplitude signal after gain adjustment is lower than an ADC overflow threshold of the transceiver unit.

8. A receiver, characterized in that: The invention comprises the radio frequency receiving circuit as claimed in any one of claims 1 to 7.

9. A base station, characterized in that: It comprises a base station antenna and the receiver as claimed in claim 8.

10. The base station according to claim 9, characterized in that The base station is a NB-IOT base station.

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