Low noise amplifier

Abstract

The invention provides a low noise amplifier. The low-noise amplifier comprises a first-stage amplification circuit, a second-stage amplification circuit and at least one third-stage amplification circuit, the first-stage amplification circuit, the second-stage amplification circuit and the third-stage amplification circuits are connected in sequence and are used for amplifying input signals stage by stage and outputting the signals amplified stage by stage; a resonant network is arranged in the third-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmitting frequency band is within a preset error range, so that signals in the transmitting frequency band are coupled to the ground. According to the invention, the performance of the whole receiving link can be considered while the transmitting frequency band signal is suppressed.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a low noise amplifier. Background Art

[0002] As an important part of the receiving link of the communication system, the performance of the low noise amplifier directly affects the key indicators of the entire system, such as sensitivity, signal-to-noise ratio and dynamic range. In complex communication environments, especially in systems using phased array antenna technology, the power amplifier in the transmitting link and the low noise amplifier in the receiving link are often integrated on the same array. Although this design improves the integration and flexibility of the system, it also brings a severe challenge: the signal in the transmitting frequency band may leak into the receiving link through various coupling paths, especially when the transmitting power is high or the receiving frequency band is close to the transmitting frequency band, this leakage phenomenon is particularly obvious. The leakage signal will act as an interference source, significantly increasing the noise level of the low noise amplifier in the receiving link, thereby affecting the communication quality of the receiving link.

[0003] To address the above problems, the traditional solution is to add a bandpass filter at the input stage of the low noise amplifier in the receiving link to suppress the transmitted frequency band signal. However, the input stage bandpass filter will significantly increase the noise figure of the entire receiving link, resulting in a significant deterioration in the performance of the entire receiving link. Summary of the invention

[0004] The embodiment of the present invention provides a low noise amplifier to solve the problem in the related art that it is impossible to suppress the signal in the transmission frequency band while taking into account the performance of the entire receiving link.

[0005] In a first aspect, an embodiment of the present invention provides a low noise amplifier, comprising: a first-stage amplifier circuit, a second-stage amplifier circuit, and at least one third-stage amplifier circuit;

[0006] The first-stage amplifying circuit, the second-stage amplifying circuit, and the third-stage amplifying circuits are connected in sequence to amplify the input signal step by step and output the amplified signal step by step;

[0007] A resonant network is arranged inside the three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency band is within a preset error range, so as to couple the signal in the transmission frequency band to the ground.

[0008] In a possible implementation, the three-stage amplification circuit includes: a first capacitor, a resonant network, and an amplification network;

[0009] The negative electrode of the first capacitor is connected to the signal output end of the second-stage amplifier circuit, or the signal output end of the last third-stage amplifier circuit;

[0010] The negative electrode of the first capacitor is also connected to the first end of the amplification network;

[0011] The positive electrode of the first capacitor is respectively connected to the resonant network, the second end of the amplifying network, and a first external power source;

[0012] The third end of the amplifying network is connected to the signal input end of the next three-stage amplifying circuit, or the third end of the amplifying network is connected to a second external power supply and is used to output the signal amplified step by step.

[0013] In a possible implementation, the resonant network includes: a first inductor and a second capacitor;

[0014] The first inductor and the second capacitor are connected in series, and one end of the series connection is respectively connected to the positive electrode of the first capacitor, the second end of the amplification network, and the first external power supply;

[0015] The other end of the series connection is grounded.

[0016] In a possible implementation, the amplification network includes: a first switch tube, a second inductor and a third capacitor;

[0017] The gate of the first switch tube is respectively connected to the resonant network, the positive electrode of the first capacitor, and the first external power supply;

[0018] The source electrode of the first switch tube is respectively connected to one end of the second inductor and the positive electrode of the third capacitor;

[0019] The other end of the second inductor is connected to the negative electrode of the first capacitor;

[0020] The negative electrode of the third capacitor is grounded;

[0021] The drain of the first switch tube is connected to the signal input end of the next three-stage amplifier circuit, or the drain of the first switch tube is connected to the second external power supply and is used to output the signal amplified step by step.

[0022] In a possible implementation, the first-stage amplification circuit includes: a second switch tube and a bias network;

[0023] The gate of the second switch tube is used to receive an input signal, and the gate of the second switch tube is also connected to the first end of the bias network;

[0024] The second end of the bias network is connected to a third external power source, and the third end of the bias network is grounded;

[0025] The source of the second switch tube is grounded, and the drain of the second switch tube is connected to the signal input end of the secondary amplifier circuit.

[0026] In a possible implementation, the bias network includes: a third inductor and a fourth capacitor;

[0027] One end of the third inductor is connected to the gate of the second switch tube;

[0028] The other end of the third inductor is connected to the third external power source and the positive electrode of the fourth capacitor respectively;

[0029] A negative electrode of the fourth capacitor is grounded.

[0030] In a possible implementation, the secondary amplifier circuit includes: a fifth capacitor, a fourth inductor, a sixth capacitor and a third switch tube;

[0031] The negative electrode of the fifth capacitor and one end of the fourth inductor are both connected to the signal output end of the first-stage amplifier circuit;

[0032] The positive electrode of the fifth capacitor is respectively connected to the gate of the third switch tube and the fourth external power supply;

[0033] The other end of the fourth inductor is respectively connected to the source of the third switch tube and the positive electrode of the sixth capacitor;

[0034] The negative electrode of the sixth capacitor is grounded;

[0035] The drain of the third switch tube is connected to the signal input end of the three-stage amplifier circuit.

[0036] In a possible implementation, the low noise amplifier further includes: at least one first voltage divider circuit and a second voltage divider circuit; the first voltage divider circuit corresponds to the three-stage amplification circuit in a one-to-one manner;

[0037] The at least one first voltage-dividing circuit and the second voltage-dividing circuit are connected in sequence step by step;

[0038] Wherein, the power input end of the first voltage divider circuit is connected to a second external power supply, or connected to a first power output end of a previous first voltage divider circuit;

[0039] The first power supply output terminal of the first voltage divider circuit is connected to the power supply input terminal of the next first voltage divider circuit, or connected to the power supply input terminal of the second voltage divider circuit;

[0040] The second power supply output terminal of the first voltage divider circuit is used to provide a first external power supply for the corresponding three-stage amplification circuit;

[0041] The power input end of the second voltage divider circuit is connected to the first power output end of the first voltage divider circuit adjacent to the second voltage divider circuit;

[0042] The power output terminal of the second voltage divider circuit is used to provide a fourth external power supply for the secondary amplifier circuit.

[0043] In a possible implementation, the first voltage divider circuit includes: a first resistor and a second resistor;

[0044] The first end of the first resistor is connected to a second external power supply, or connected to a first power supply output end of a first voltage divider circuit;

[0045] The second end of the first resistor is connected to the power input end of the next first voltage divider circuit, or connected to the power input end of the second voltage divider circuit;

[0046] The second end of the first resistor is also connected to the first end of the second resistor;

[0047] The second end of the second resistor is used to provide a first external power supply for the corresponding three-stage amplification circuit.

[0048] In a possible implementation, the second voltage divider circuit includes: a third resistor, a fourth resistor, and a fifth resistor;

[0049] The first end of the third resistor is connected to the first power supply output end of the first voltage dividing circuit adjacent to the second voltage dividing circuit;

[0050] The second end of the third resistor is respectively connected to the first end of the fourth resistor and the first end of the fifth resistor;

[0051] The other end of the fourth resistor is grounded;

[0052] The second end of the fifth resistor is used to provide a fourth external power supply for the secondary amplifier circuit.

[0053] The embodiment of the present invention provides a low noise amplifier, which couples the signal in the transmission frequency band to the ground by setting a resonant network in a three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency is within a preset error range, so as to achieve effective suppression of the signal in the transmission frequency band. In addition, compared with the method of setting a bandpass filter at the input stage of the low noise amplifier, the embodiment of the present invention suppresses the signal by resonant coupling in the three-stage amplification circuit (i.e., the back end of the signal amplification), which can effectively reduce the noise impact of the resonant network on the overall receiving link, thereby weakening the impact of the resonant network on the receiving link and avoiding the deterioration of the receiving link performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0055] Figure 1 is a schematic diagram of the structure of a low noise amplifier provided by an embodiment of the present invention;

[0056] Figure 2 is a schematic structural diagram of a low noise amplifier provided by another embodiment of the present invention;

[0057] Figure 3 It is a structural schematic diagram of a low noise amplifier provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0059] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, rather than to describe a specific order.

[0060] In a phased array antenna system, the power amplifier in the transmitting link and the low-noise amplifier in the receiving link are often integrated on the same array plane, which makes it possible for the signal in the transmitting frequency band to leak into the receiving link through various coupling paths, thereby affecting the communication quality of the receiving link. In related technologies, a bandpass filter is usually added to the input stage of the low-noise amplifier in the receiving link to suppress the signal in the transmitting frequency band. However, setting a bandpass filter at the input stage will significantly increase the noise coefficient of the entire receiving link, thereby significantly deteriorating the performance of the entire receiving link.

[0061] In order to suppress the signal in the transmission frequency band while taking into account the performance of the entire receiving link, the present application provides a low-noise amplifier, which includes a first-stage amplifier circuit, a second-stage amplifier circuit and at least one third-stage amplifier circuit connected in sequence, and a resonant network is set in the third-stage amplifier circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency band is within a preset error range, which is used to couple the signal in the transmission frequency band to the ground. On the one hand, the resonant network can couple the signal in the transmission frequency band to the ground, thereby suppressing the signal in the transmission frequency band. On the other hand, by setting the resonant network in the third-stage amplifier circuit (i.e., the back end of the signal amplification), the noise impact of the resonant network on the overall receiving link can be effectively reduced, avoiding the deterioration of the receiving link performance.

[0062] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0063] Figure 1 A schematic diagram of the structure of a low noise amplifier provided by an embodiment of the present invention. Figure 1 The low noise amplifier includes: a first-stage amplifier circuit 11, a second-stage amplifier circuit 12 and at least one third-stage amplifier circuit 13.

[0064] The first-stage amplifier circuit 11, the second-stage amplifier circuit 12, and the third-stage amplifier circuit 13 are connected in sequence to amplify the input signal step by step and output the amplified signal step by step.

[0065] A resonant network is arranged inside the three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency band is within a preset error range, so as to couple the signal in the transmission frequency band to the ground.

[0066] It should be noted that Figure 1 As an exemplary figure, two three-stage amplifier circuits are shown, but this does not serve as a specific limitation on the number of three-stage amplifier circuits. The number of three-stage amplifier circuits can be determined according to actual conditions, and the embodiment of the present invention does not make a specific limitation on this.

[0067] by Figure 1 For example, the first-stage amplifier circuit 11 is used to receive an input signal, perform a first-stage amplification on the input signal, and input the amplified signal to the second-stage amplifier circuit 12. The second-stage amplifier circuit 12 continues to perform a second-stage amplification on the signal, and inputs the amplified signal to the third-stage amplifier circuit 13 connected to the second-stage amplifier circuit, so as to continue to amplify the signal, and input the amplified signal to the next third-stage amplifier circuit. The next third-stage amplifier circuit continues to amplify the signal and outputs the amplified signal.

[0068] A resonant network is provided in each three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency band is within a preset error range, which is used to couple the signal in the transmission frequency band to the ground, thereby effectively suppressing the signal in the transmission frequency band.

[0069] Among them, the three-stage amplifier circuit is at the signal amplification back end of the entire low-noise amplifier. Compared with the method of setting a bandpass filter at the input stage of the low-noise amplifier, the embodiment of the present invention sets a resonant network in the three-stage amplifier circuit, which can effectively weaken the influence of the resonant network on the noise coefficient of the entire receiving link and avoid the deterioration of the receiving link performance.

[0070] Compared with the prior art, the embodiment of the present invention couples the signal in the transmission frequency band to the ground by setting a resonant network in the three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency is within a preset error range, so as to achieve effective suppression of the signal in the transmission frequency band. Moreover, compared with the method of setting a bandpass filter at the input stage of the low-noise amplifier, the embodiment of the present invention suppresses the signal by resonant coupling in the three-stage amplification circuit (i.e., the back end of the signal amplification), which can effectively reduce the noise impact of the resonant network on the overall receiving link, thereby weakening the impact of the resonant network on the receiving link and avoiding the deterioration of the receiving link performance.

[0071] Optional, see Figure 2 The three-stage amplifier circuit 13 includes: a first capacitor C1, a resonant network 131 and an amplifier network 132.

[0072] The negative electrode of the first capacitor C1 is connected to the signal output end of the secondary amplifier circuit 12, or the signal output end of the last tertiary amplifier circuit;

[0073] The negative electrode of the first capacitor C1 is also connected to the first end of the amplification network 132;

[0074] The positive electrode of the first capacitor C1 is respectively connected to the resonant network 131, the second end of the amplifying network 132, and the first external power source;

[0075] The third end of the amplifier network 132 is connected to the signal input end of the next three-stage amplifier circuit, or the third end of the amplifier network 132 is connected to the second external power supply and is used to output the signal after being amplified step by step.

[0076] Here, the negative electrode of the first capacitor C1 is the signal input terminal of the three-stage amplifier circuit, and the third terminal of the amplifier network is the signal output terminal of the three-stage amplifier circuit. When the three-stage amplifier circuit is adjacent to the two-stage amplifier circuit, the negative electrode of the first capacitor is connected to the signal output terminal of the two-stage amplifier circuit. When the three-stage amplifier circuit is adjacent to the previous three-stage amplifier circuit, the negative electrode of the first capacitor is connected to the signal output terminal of the previous three-stage amplifier circuit.

[0077] Similarly, when the three-stage amplifier circuit is adjacent to the next three-stage amplifier circuit, the third end of the amplifier network is connected to the signal input end of the next three-stage amplifier circuit. When the three-stage amplifier circuit is used as the last amplifier circuit in the low-noise amplifier circuit, the third end of the amplifier network is used as the output end of the low-noise amplifier, connected to the second external power supply, and used to output the signal after step-by-step amplification.

[0078] For each three-stage amplifier circuit, the first capacitor C1 is used to receive the output signal of the previous stage amplifier circuit, and couple the output signal to the resonant network 131 and the second end of the amplifier network 132. The resonant network 131 is used to couple the transmission frequency band signal in the signal to the ground, thereby effectively suppressing the transmission frequency band signal. The second end of the amplifier network 132, as the signal input end of the amplifier network 132, is used to amplify the signal after suppressing the transmission frequency band and output it through the third end of the amplifier network 132.

[0079] Optional, see Figure 2 , the resonant network 131 includes: a first inductor L1 and a second capacitor C2;

[0080] The first inductor L1 and the second capacitor C2 are connected in series, and one end of the series connection is respectively connected to the positive electrode of the first capacitor C1, the second end of the amplifying network 132, and the first external power supply;

[0081] The other end of the series connection is grounded.

[0082] For example, an LC series resonant network is used in the embodiment of the present invention to suppress the transmission frequency band signal. Users can also use other types of resonant networks according to actual conditions, such as an LC parallel resonant network.

[0083] Optionally, the amplifying network 132 includes: a first switch tube Q1, a second inductor L2 and a third capacitor C3;

[0084] The gate of the first switch tube Q1 is respectively connected to the resonant network 131, the positive electrode of the first capacitor C1, and the first external power source;

[0085] The source of the first switch tube Q1 is respectively connected to one end of the second inductor L2 and the positive electrode of the third capacitor C3;

[0086] The other end of the second inductor L2 is connected to the negative electrode of the first capacitor C1;

[0087] The negative electrode of the third capacitor C3 is grounded;

[0088] The drain of the first switch tube Q1 is connected to the signal input end of the next three-stage amplifier circuit, or the drain of the first switch tube Q1 is connected to the second external power supply and is used to output the signal after being amplified step by step.

[0089] In the embodiment of the present invention, the first switch tube Q1 is mainly used to perform signal amplification. The gate of the first switch tube Q1 is used as the signal input end of the amplification network, which is used to receive the signal to be amplified after the signal in the transmission frequency band is suppressed, and the drain of the first switch tube Q1 is used as the signal output end of the amplification network, which is used to output the amplified signal.

[0090] Here, the source of the first switch tube Q1 is provided with a second inductor L2 and a third capacitor C3, wherein the second inductor L2 is high impedance to high-frequency signals, and the third capacitor C3 provides a radio frequency low for high-frequency signals, which can block the signal path between the source of the third switch tube Q3 and the previous stage amplifier circuit, so that the output signal of the previous stage amplifier circuit is completely coupled to the gate of the first switch tube Q1 and the resonant network 131 via the first capacitor C1, so as to suppress the transmission frequency band and amplify the signal of the output signal of the previous stage amplifier circuit.

[0091] Among them, when the three-stage amplifier circuit is the last stage amplifier circuit in the low noise amplifier, the drain of the first switch tube Q1 is connected to the second external power supply and is used to output the signal after step-by-step amplification. Here, the second external power supply provides the drain voltage for the first switch tube Q1. To improve the feeding quality, refer to Figure 2 In an embodiment of the present invention, a power inductor L can be connected in series to the output end of the second external power supply, so that the output voltage of the second external power supply enters the drain of the first switch tube Q1 through the power inductor L, thereby achieving the purpose of improving the power feeding quality.

[0092] Also, see Figure 2 In order to improve the output signal quality of the low noise amplifier, when the three-stage amplifier circuit is the last stage amplifier circuit in the low noise amplifier, an output capacitor Cout can also be connected in series to the drain of the first switch tube Q1 to filter out signal noise. The negative electrode of the output capacitor Cout is connected to the drain of the first switch tube Q1, and the positive electrode of the output capacitor Cout is used to output the signal after step-by-step amplification.

[0093] Optional, see Figure 2 The first-stage amplifier circuit 11 includes: a second switch tube Q2 and a bias network 111;

[0094] The gate of the second switch tube Q2 is used to receive an input signal, and the gate of the second switch tube Q2 is also connected to the first end of the bias network 111;

[0095] The second end of the bias network 111 is connected to a third external power source, and the third end of the bias network 111 is grounded;

[0096] The source of the second switch tube Q2 is grounded, and the drain of the second switch tube Q2 is connected to the signal input end of the secondary amplifier circuit 12 .

[0097] Here, the first-stage amplifier circuit uses the second switch tube Q2 to perform signal amplification. The gate of the second switch tube Q2 serves as the signal input terminal of the first-stage amplifier circuit, and is used to receive the input signal. The drain of the second switch tube Q2 serves as the signal output terminal of the first-stage amplifier circuit, and is connected to the signal input terminal of the second-stage amplifier circuit 12, and is used to input the amplified signal to the second-stage amplifier circuit.

[0098] To improve signal quality, the embodiment of the present invention can also connect an input capacitor Cin in series with the gate of the second switch tube Q2, so that the input signal enters the gate of the second switch tube Q2 after passing through the input capacitor Cin. The input capacitor can perform capacitive filtering on the input signal to filter out signal noise. Figure 2 The negative electrode of the input capacitor Cin is used to receive the input signal, and the positive electrode of the input capacitor Cin is connected to the gate of the second switch tube Q2.

[0099] The bias network 111 is used to provide a gate bias voltage for the second switch tube Q2. Optionally, the bias network 111 includes: a third inductor L3 and a fourth capacitor C4;

[0100] One end of the third inductor L3 is connected to the gate of the second switch tube Q2;

[0101] The other end of the third inductor L3 is connected to the third external power source and the positive electrode of the fourth capacitor C4 respectively;

[0102] A negative electrode of the fourth capacitor C4 is grounded.

[0103] Optional, see Figure 2 The secondary amplifier circuit 12 includes: a fifth capacitor C5, a fourth inductor L4, a sixth capacitor C6 and a third switch tube Q3.

[0104] The negative electrode of the fifth capacitor C5 and one end of the fourth inductor L4 are both connected to the signal output end of the first-stage amplifier circuit 11;

[0105] The positive electrode of the fifth capacitor C5 is respectively connected to the gate of the third switch tube Q3 and the fourth external power supply;

[0106] The other end of the fourth inductor L4 is connected to the source of the third switch tube Q3 and the positive electrode of the sixth capacitor C6 respectively;

[0107] The negative electrode of the sixth capacitor C6 is grounded;

[0108] The drain of the third switch tube Q3 is connected to the signal input terminal of the three-stage amplifier circuit 13 .

[0109] Here, the third switch tube Q3 mainly performs signal amplification. The fifth capacitor C5 couples the output signal of the first-stage amplifier circuit 11 to the gate of the third switch tube Q3 so that the third switch tube Q3 performs signal amplification. The fourth inductor L4 has high impedance to high-frequency signals, and the sixth capacitor C6 provides a radio frequency ground for high-frequency signals to prevent the output signal of the first-stage amplifier circuit 11 from entering the source of the third switch tube Q3, causing signal interference and affecting the signal amplification work of the third switch tube Q3.

[0110] The fourth external power supply is used to provide a gate bias voltage for the third switch tube Q3 so that the third switch tube Q3 can perform a signal amplification operation.

[0111] Optional, see Figure 3 The low noise amplifier further includes: at least one first voltage divider circuit 14 and a second voltage divider circuit 15; the first voltage divider circuit 14 corresponds to the three-stage amplification circuit 13 in a one-to-one manner.

[0112] At least one first voltage divider circuit 14 is connected to the second voltage divider circuit 15 in sequence.

[0113] Here, each first voltage divider circuit provides a first external power supply to each three-stage amplifier circuit for the three-stage amplifier circuit to perform signal amplification. The second voltage divider circuit provides a fourth external power supply to the two-stage amplifier circuit for the two-stage amplifier circuit to perform signal amplification.

[0114] The embodiment of the present invention sets at least one first voltage divider circuit and a second voltage divider circuit to be connected step by step in sequence, so that at least one first voltage divider circuit and a second voltage divider circuit can divide the voltage of the same external power supply step by step to obtain different operating voltages, and provide them to each level of amplifier circuit accordingly. There is no need to provide external power supplies for each level of amplifier circuit respectively, which can effectively simplify the circuit structure.

[0115] Wherein, the power input end of the first voltage divider circuit 14 is connected to the second external power supply, or connected to the first power output end of the previous first voltage divider circuit;

[0116] The first power supply output terminal of the first voltage divider circuit 14 is connected to the power supply input terminal of the next first voltage divider circuit, or connected to the power supply input terminal of the second voltage divider circuit 15;

[0117] The second power supply output terminal of the first voltage divider circuit 14 is used to provide a first external power supply for the corresponding three-stage amplification circuit 13;

[0118] The power input end of the second voltage divider circuit 15 is connected to the first power output end of the first voltage divider circuit adjacent to the second voltage divider circuit;

[0119] The power output terminal of the second voltage divider circuit 15 is used to provide a fourth external power supply for the secondary amplifier circuit 12 .

[0120] It can be understood that if the three-stage amplifier circuit corresponding to the first voltage divider circuit is the last-stage amplifier circuit in the low-noise amplifier, the first power input terminal of the first voltage divider circuit is connected to the second external power supply. If the three-stage amplifier circuit corresponding to the first voltage divider circuit is not the last-stage amplifier circuit in the low-noise amplifier, the first power input terminal of the first voltage divider circuit is connected to the first power output terminal of the previous first voltage divider circuit.

[0121] Optionally, the first voltage divider circuit includes: a first resistor R1 and a second resistor R2;

[0122] A first end of the first resistor R1 is connected to a second external power supply, or connected to a first power supply output end of a first voltage divider circuit;

[0123] The second end of the first resistor R1 is connected to the power input end of the next first voltage divider circuit, or connected to the power input end of the second voltage divider circuit;

[0124] The second end of the first resistor R1 is also connected to the first end of the second resistor R2;

[0125] The second end of the second resistor R2 is used to provide a first external power supply for the corresponding three-stage amplification circuit.

[0126] Optionally, the second voltage divider circuit includes: a third resistor R3, a fourth resistor R4 and a fifth resistor R5;

[0127] A first end of the third resistor R3 is connected to a first power supply output end of a first voltage dividing circuit adjacent to the second voltage dividing circuit;

[0128] The second end of the third resistor R3 is respectively connected to the first end of the fourth resistor R4 and the first end of the fifth resistor R5;

[0129] The other end of the fourth resistor R4 is grounded;

[0130] The second end of the fifth resistor R5 is used to provide a fourth external power supply for the secondary amplifying circuit.

[0131] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low noise amplifier, characterized in that: include: a primary amplifying circuit, a secondary amplifying circuit and at least one tertiary amplifying circuit; The first-stage amplifying circuit, the second-stage amplifying circuit, and the third-stage amplifying circuits are connected in sequence to amplify the input signal step by step and output the amplified signal step by step; A resonant network is arranged inside the three-stage amplification circuit, and the frequency difference between the resonant frequency of the resonant network and the transmission frequency band is within a preset error range, so as to couple the signal in the transmission frequency band to the ground.

2. The low noise amplifier according to claim 1, characterized in that The three-stage amplification circuit comprises: a first capacitor, a resonant network and an amplification network; The negative electrode of the first capacitor is connected to the signal output end of the second-stage amplifier circuit, or the signal output end of the last third-stage amplifier circuit; The negative electrode of the first capacitor is also connected to the first end of the amplification network; The positive electrode of the first capacitor is respectively connected to the resonant network, the second end of the amplifying network, and the first external power supply; The third end of the amplifying network is connected to the signal input end of the next three-stage amplifying circuit, or the third end of the amplifying network is connected to a second external power supply and is used to output the signal amplified step by step.

3. The low noise amplifier according to claim 2, characterized in that The resonant network comprises: a first inductor and a second capacitor; The first inductor and the second capacitor are connected in series, and one end of the series connection is respectively connected to the positive electrode of the first capacitor, the second end of the amplification network, and the first external power supply; The other end of the series connection is grounded.

4. The low noise amplifier according to claim 2 or 3, characterized in that: The amplifying network includes: a first switch tube, a second inductor and a third capacitor; The gate of the first switch tube is respectively connected to the resonant network, the positive electrode of the first capacitor, and the first external power supply; The source electrode of the first switch tube is respectively connected to one end of the second inductor and the positive electrode of the third capacitor; The other end of the second inductor is connected to the negative electrode of the first capacitor; The negative electrode of the third capacitor is grounded; The drain of the first switch tube is connected to the signal input end of the next three-stage amplifier circuit, or the drain of the first switch tube is connected to the second external power supply and is used to output the signal amplified step by step.

5. The low noise amplifier according to any one of claims 1 to 3, characterized in that: The first-stage amplifier circuit includes: a second switch tube and a bias network; The gate of the second switch tube is used to receive an input signal, and the gate of the second switch tube is also connected to the first end of the bias network; The second end of the bias network is connected to a third external power source, and the third end of the bias network is grounded; The source of the second switch tube is grounded, and the drain of the second switch tube is connected to the signal input end of the secondary amplifier circuit.

6. The low noise amplifier according to claim 5, characterized in that The bias network includes: a third inductor and a fourth capacitor; One end of the third inductor is connected to the gate of the second switch tube; The other end of the third inductor is connected to the third external power source and the positive electrode of the fourth capacitor respectively; A negative electrode of the fourth capacitor is grounded.

7. The low noise amplifier according to any one of claims 1 to 3, characterized in that: The secondary amplifier circuit comprises: a fifth capacitor, a fourth inductor, a sixth capacitor and a third switch tube; The negative electrode of the fifth capacitor and one end of the fourth inductor are both connected to the signal output end of the first-stage amplifier circuit; The positive electrode of the fifth capacitor is respectively connected to the gate of the third switch tube and the fourth external power supply; The other end of the fourth inductor is respectively connected to the source of the third switch tube and the positive electrode of the sixth capacitor; The negative electrode of the sixth capacitor is grounded; The drain of the third switch tube is connected to the signal input end of the three-stage amplifier circuit.

8. The low noise amplifier according to claim 2 or 3, characterized in that: The low noise amplifier further comprises: at least one first voltage divider circuit and a second voltage divider circuit; the first voltage divider circuit corresponds to the three-stage amplification circuit in a one-to-one manner; The at least one first voltage-dividing circuit and the second voltage-dividing circuit are connected in sequence step by step; Wherein, the power input end of the first voltage divider circuit is connected to a second external power supply, or connected to a first power output end of a previous first voltage divider circuit; The first power supply output terminal of the first voltage divider circuit is connected to the power supply input terminal of the next first voltage divider circuit, or connected to the power supply input terminal of the second voltage divider circuit; The second power supply output terminal of the first voltage divider circuit is used to provide a first external power supply for the corresponding three-stage amplification circuit; The power input end of the second voltage divider circuit is connected to the first power output end of the first voltage divider circuit adjacent to the second voltage divider circuit; The power output terminal of the second voltage divider circuit is used to provide a fourth external power supply for the secondary amplifier circuit.

9. The low noise amplifier according to claim 8, characterized in that The first voltage divider circuit includes: a first resistor and a second resistor; The first end of the first resistor is connected to a second external power supply, or connected to a first power supply output end of a first voltage divider circuit; The second end of the first resistor is connected to the power input end of the next first voltage divider circuit, or connected to the power input end of the second voltage divider circuit; The second end of the first resistor is also connected to the first end of the second resistor; The second end of the second resistor is used to provide a first external power supply for the corresponding three-stage amplification circuit.

10. The low noise amplifier according to claim 8, characterized in that The second voltage divider circuit includes: a third resistor, a fourth resistor and a fifth resistor; The first end of the third resistor is connected to the first power supply output end of the first voltage dividing circuit adjacent to the second voltage dividing circuit; The second end of the third resistor is respectively connected to the first end of the fourth resistor and the first end of the fifth resistor; The other end of the fourth resistor is grounded; The second end of the fifth resistor is used to provide a fourth external power supply for the secondary amplifier circuit.

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