A negative feedback ultra-wideband low noise amplifier circuit and a design method thereof

Abstract

This invention discloses a negative feedback ultrawideband low-noise amplifier circuit and its design method, comprising at least an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network, and an output matching network. The input matching network is used to match a 50-ohm impedance to the minimum noise impedance point of the transistor, minimizing noise in the power amplifier while achieving wideband matching for the low-noise amplifier. Its input terminal is connected to a signal source, and its output terminal is sequentially connected to the first, second, and third amplifiers. Each amplifier stage is connected to the first, second, and third negative feedback networks, respectively. The structure proposed in this invention improves the noise performance and gain flatness of the low-noise amplifier while achieving a working bandwidth spanning the S-band, C-band, and X-band.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency circuit design, and more particularly, to a negative feedback ultra-wideband low noise amplifier circuit and a design method thereof. BACKGROUND

[0002] With the further development of communication system technology, the 5G communication system has higher requirements for data transmission rate. As a key technology for high-speed short-range wireless communication, the wideband amplifier technology has been increasingly widely used in the fields of wireless communication, radar, positioning, etc. due to its wide frequency band, high data transmission rate, low power consumption, anti-interference and other advantages. As a key part of the receiver front end, the wideband low noise amplifier is located at the forefront of the entire receiver, and its performance will directly affect the sensitivity, transmission rate, error rate and other performances of the receiving system.

[0003] With the explosive growth of communication data, the bandwidth requirement for communication frequency band is becoming wider and wider. Compared with the traditional narrow-band matched low noise amplifier, wide-band matching brings higher challenges to the design of low noise amplifier. At the same time, in order to ensure the signal quality and stability during transmission, the gain fluctuation in the working frequency band of the ultra-wideband puts higher requirements on the design of the low noise amplifier.

[0004] Therefore, in view of the needs and challenges existing in the prior art, it is necessary to conduct research and design improvement to provide a new topology to realize the design of the ultra-wideband low noise amplifier. SUMMARY

[0005] In view of the insufficient design of the existing wideband low noise amplifier in terms of bandwidth matching and in-band gain flatness, the present application provides a negative feedback ultra-wideband low noise amplifier circuit, which improves the narrow-band matching structure of the traditional low noise amplifier, widens the working frequency bandwidth of the low noise amplifier through Chebyshev band-pass filter input matching and Chebyshev band-pass filter output matching. The drain parallel negative feedback and source series inductance negative feedback of each stage are optimized, which reduces the high gain of the transistor itself in the low frequency band, so that the low noise amplifier can obtain a wider working bandwidth while reducing the gain fluctuation of the circuit in the wide working frequency band.

[0006] In order to solve the technical problems existing in the prior art, the technical scheme of the present application is as follows:

[0007] A negative feedback ultra-wideband low noise amplifier circuit, at least comprising an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network and an output matching network, wherein,

[0008] The input matching network is used to match 50 ohm impedance to the minimum noise impedance point of the transistor, so that the power amplifier obtains the minimum noise and completes the broadband matching of the low noise amplifier; the input end of the input matching network is connected with a signal source, and the output end is connected with a first amplifier, a second amplifier and a third amplifier in sequence; each amplifier is connected with a first negative feedback network, a second negative feedback network and a third negative feedback network respectively.

[0009] The first amplifier adopts optimal noise matching, and realizes the radio frequency broadband matching and the low noise amplification in combination with the input matching network;

[0010] The second amplifier and the third amplifier both adopt maximum power matching, and are used to realize the function of high gain amplification.

[0011] The input end of the output matching network is connected with the output end of the third amplifier, and is used to match 50 ohm impedance to the highest gain impedance point of the transistor, so that the power amplifier obtains the best gain and completes the broadband matching of the low noise amplifier.

[0012] As a further improved scheme, the input matching network and the output matching network both adopt Chebyshev band-pass filter network structure.

[0013] As a further improved scheme, the first negative feedback network, the second negative feedback network and the third negative feedback network all adopt drain parallel negative feedback circuit structure and source series inductance negative feedback circuit structure.

[0014] As a further improved scheme, the first amplifier, the second amplifier and the third amplifier all adopt HEMT device.

[0015] As a further improved scheme, the equivalent circuit of the drain parallel negative feedback circuit structure comprises feedback resistance R fb , gate-source capacitance C gs , transconductance g m , gate current i1, drain current i2, voltage V1 between the gate and the source, and voltage V2 between the drain and the source in sequence.

[0016] The admittance matrix of the equivalent circuit is:

[0017]

[0018] The corresponding S parameter is:

[0019]

[0020]

[0021]

[0022] where Z0 is the characteristic impedance, R fb is a parallel feedback resistor;

[0023] When matched, S 11 = S 22 = 0, the input-output return loss VSWR = 1, from which it follows that:

[0024] R fb = g m Z0 2

[0025] Thus,

[0026]

[0027] By optimizing the tuning of the resistance, the purpose of controlling the gain flatness is achieved.

[0028] As a further improvement, the equivalent circuit of the source series inductance negative feedback circuit structure comprises in turn a gate resistor R g , a gate-source capacitance C gs and its voltage drop V c , an interelectrode transconductance g m , a source series inductance L s , a voltage V g between the gate and the source, a gate current i g , and a current i s between the drain and the source;

[0029] where:

[0030]

[0031] S = jw

[0032]

[0033] Replacing s with jw, we obtain the frequency response of the input impedance as:

[0034]

[0035] The real and imaginary parts of the impedance are separated:

[0036] Z in = R g + R a + j(X ls - X cgs )

[0037] The input impedance of the transistor itself is:

[0038] Z in = R g - jX cgs

[0039] Using a section of microstrip line instead of inductance as feedback is advantageous for achieving noise matching and power matching simultaneously.

[0040] The application also discloses a design method of the negative feedback ultra-wideband low-noise amplifier circuit, and at least comprises the following steps:

[0041] Step 1: a negative feedback ultra-wideband low-noise amplifier circuit structure based on a Chebyshev band-pass filter matching network is designed, and at least comprises an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network and an output matching network, wherein the input matching network and the output matching network both adopt a Chebyshev band-pass filter network structure.

[0042] Step 2: a drain parallel negative feedback circuit and a source series inductance negative feedback circuit are designed, wherein the equivalent circuit of the drain parallel negative feedback circuit comprises a feedback resistor R fb , a gate-source capacitance C gs , a transconductance g m , a gate current i1, a drain current i2, a voltage V1 between the gate and the source, and a voltage V2 between the drain and the source in sequence.

[0043]

[0044] Corresponding S parameters are as follows:

[0045]

[0046]

[0047]

[0048] Wherein Z0 is a characteristic impedance, R fb is a parallel feedback resistor.

[0049] When matched, S 11 =S 22 =0, and input-output return loss VSWR=1, at this time, R

[0050] =R fb =g m Z0 2

[0051] Therefore,

[0052]

[0053] By optimizing and tuning the resistor, the gain flatness is controlled.

[0054] The equivalent circuit of the transistor source series inductance negative feedback circuit structure includes gate resistance R g , gate-source capacitance C gs and its voltage drop V c , interelectrode transconductance g m , source series inductance L s , voltage V g between the gate and the source, gate current i g , and current i s between the drain and the source in turn.

[0055] In the equivalent circuit of the transistor source series inductance negative feedback, the relationship between the parameters is calculated and analyzed as follows:

[0056]

[0057] S = jw

[0058]

[0059] Replacing s with jw, the frequency response of the input impedance is obtained as follows:

[0060]

[0061] The real part and the imaginary part of the impedance are separated

[0062] Z in = R g + R a + j (X ls - X cgs )

[0063] The input impedance of the transistor itself is

[0064] Z in = R g - jX cgs

[0065] When an ideal inductance is connected in series with the source, the input impedance increases by R a + jX ls ; making Z in closer to the optimal reflection coefficient, the matching performance is greatly improved, so an ideal inductance is connected in series with the source.

[0066] A microstrip line is used instead of the inductance to achieve a compromise between the standing wave ratio, the noise figure, and the amplifier gain.

[0067] Step 3: A Chebyshev bandpass filter topology is designed for broadband matching of a low-noise amplifier, wherein

[0068] The input matching network and the output matching network correspond to the LC part of the left half and the LC part of the right half respectively, which are sensitive to low frequency, and the input matching network and the output matching network correspond to the LC part of the right half and the LC part of the left half respectively, which are sensitive to high frequency; by selecting appropriate parameters, the impedance locus is compressed and knotted at the center of the Smith chart, realizing the broadband matching of the low-noise amplifier.

[0069] As a further improvement, step 3 further comprises the following steps:

[0070] According to the transmission line theory, when the load end is connected to the source end through a transmission line, the reflection coefficient of the load end will rotate clockwise by an angle of 2 times the electrical length of the transmission line with the characteristic impedance of the transmission line as the center, so that S 11 The center frequency f0 point of the curve moves clockwise along the dashed circle to the pure resistance axis of the Smith chart;

[0071] In the case of keeping f0 unchanged in the S 11 In the case of keeping f0 unchanged in the S

[0072] Y = jY0(tanβl-cotβl)

[0073] Where β is the phase constant, and l is the geometric length of the transmission line. In order to keep the position of f0 unchanged, the electrical length of the parallel branch microstrip stub is set to 45°; since the length of the parallel microstrip line is determined in the actual circuit, the electrical length of the parallel microstrip line will be greater than 45° at the high frequency band, and the S 11 The curve moves clockwise along the constant admittance circle; similarly, the electrical length of the parallel microstrip line will be less than 45° at the low frequency band, and the S 11 The curve moves counterclockwise along the constant admittance circle, so that the S 11 The curve is folded inward and knotted;

[0074] In the ADS schematic simulation, the characteristic impedance, electrical length and other parameters are optimized, and the S 11 The curve is matched to the specified constant input VSWR circle, realizing the broadband matching of the ultra-wideband low-noise amplifier by the Chebyshev bandpass filter network.

[0075] Each stage of the negative feedback network adopts a drain parallel negative feedback circuit and a source series inductance negative feedback circuit. The power gain of the transistor is reduced by the negative feedback network with a decrease of 6dB per octave. The gain roll-off is compensated to reduce the gain at low frequency and improve the gain at high frequency, thereby improving the in-band gain flatness of the low-noise amplifier.

[0076] The aforementioned negative feedback ultrawideband low-noise amplifier circuit based on Chebyshev bandpass filter matching network is applied in a wide frequency range of 2–11 GHz, covering the S-band, C-band and X-band RF signal range.

[0077] The input-output matching network described above adopts a Chebyshev bandpass filter network structure, which includes two series LC parts in the series branch and a parallel LC part in the parallel branch.

[0078] The input of the Chebyshev bandpass filter input matching network is connected to the signal source, and the output is connected to the input of the transistor. Optimal noise matching is performed at the source end, matching the 50-ohm impedance to the minimum noise impedance point of the transistor, so that the power amplifier obtains an ideal noise figure.

[0079] The transistors at each stage employ HEMT (High-Efficiency Media Transfer) technology, leveraging the superior noise performance of HEMT devices at high frequencies. The first amplifier provides minimal noise amplification of the RF input signal; the second and third amplifiers provide maximum gain amplification of the signal transmitted from the previous stage. The overall circuit uses a three-stage cascade configuration to achieve low-noise amplification of the RF signal within the operating frequency band.

[0080] The negative feedback network employs a drain-parallel negative feedback circuit and a source-series inductor negative feedback circuit. The drain-parallel negative feedback uses an RLC series network, feeding back the transistor output signal to the transistor input to generate negative feedback at low frequencies and positive feedback at high frequencies, reducing gain fluctuations across the circuit's wide operating bandwidth. The source-series inductor negative feedback connects the transistor source to ground via an inductor. In this invention, to avoid affecting the circuit's performance at high frequencies, a microstrip line is used instead of an inductor, which also serves as feedback to aid in power matching and noise matching.

[0081] The input of the Chebyshev bandpass filter output matching network is connected to the output of the third amplifier, which is used to match the maximum gain output impedance of the transistor to 50 ohms, so that the power amplifier can achieve maximum gain transmission.

[0082] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0083] The narrow-band matching structure of the traditional low noise amplifier is improved, and the working frequency bandwidth of the low noise amplifier is widened through Chebyshev band-pass filter input matching and Chebyshev band-pass filter output matching. The drain parallel negative feedback and the source series inductance negative feedback of each stage are optimized, the high gain of the transistor itself in the low frequency band is reduced, so that the low noise amplifier can obtain a wider working bandwidth, and the gain fluctuation of the circuit in the wide working frequency band is reduced. The power and noise are matched at the same time through the source series inductance method, and the performance of the ultra-wideband low noise amplifier is improved. BRIEF DESCRIPTION OF DRAWINGS

[0084] Figure 1 is a structure block diagram of a negative feedback ultra-wideband low noise amplifier of an embodiment of the present application;

[0085] Figure 2 is a single-stage negative feedback amplification circuit schematic diagram of a negative feedback ultra-wideband low noise amplifier based on a Chebyshev band-pass filter matching network of an embodiment of the present application;

[0086] Figure 3 is a drain parallel negative feedback equivalent circuit schematic diagram of a negative feedback ultra-wideband low noise amplifier based on a Chebyshev band-pass filter matching network of an embodiment of the present application;

[0087] Figure 4 is a transistor source series inductance negative feedback equivalent circuit diagram of a negative feedback ultra-wideband low noise amplifier based on a Chebyshev band-pass filter matching network of an embodiment of the present application;

[0088] Figure 5 is a Chebyshev band-pass filter matching network circuit schematic diagram of a negative feedback ultra-wideband low noise amplifier based on a Chebyshev band-pass filter matching network of an embodiment of the present application;

[0089] Figure 6 is an S 11 simulation result diagram;

[0090] Figure 7 is an S 11 simulation result diagram;

[0091] Figure 8 is a gain and return loss simulation result diagram of a negative feedback ultra-wideband low noise amplifier based on a Chebyshev band-pass filter matching network of an embodiment of the present application;

[0092] Figure 9is a noise figure simulation result diagram of the negative feedback ultra-wideband low noise amplifier based on Chebyshev band-pass filter matching network of the embodiment of the application;

[0093] Figure 10 is a stability coefficient simulation result diagram of the negative feedback ultra-wideband low noise amplifier based on Chebyshev band-pass filter matching network of the embodiment of the application; DETAILED DESCRIPTION

[0094] The specific embodiments of the application will be further described below with reference to the embodiments and the accompanying drawings:

[0095] Referring to Figure 1 , a principle schematic diagram of a negative feedback ultra-wideband low noise amplifier circuit of the application is shown, which at least comprises an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network and an output matching network, wherein,

[0096] The input matching network is used for matching 50 ohm impedance to the minimum noise impedance point of a transistor, so that the power amplifier obtains minimum noise and completes the broadband matching of the low noise amplifier at the same time; the input end of the input matching network is connected with a signal source, and the output end is connected with the first amplifier, the second amplifier and the third amplifier in sequence; each stage of amplifier is connected with the first negative feedback network, the second negative feedback network and the third negative feedback network respectively.

[0097] The first amplifier adopts optimal noise matching, and realizes low noise amplification while realizing radio frequency broadband matching in combination with the input matching network.

[0098] The second amplifier and the third amplifier both adopt maximum power matching, and are used for realizing the function of high gain amplification.

[0099] The input end of the output matching network is connected with the output end of the third amplifier, and is used for matching 50 ohm impedance to the highest gain impedance point of a transistor, so that the power amplifier obtains optimal gain and completes the broadband matching of the low noise amplifier at the same time.

[0100] The input matching network and the output matching network both adopt Chebyshev band-pass filter network structure.

[0101] The first negative feedback network, the second negative feedback network and the third negative feedback network all adopt drain parallel negative feedback circuit structure and source series inductance negative feedback circuit structure.

[0102] The first amplifier, the second amplifier and the third amplifier all adopt HEMT devices.

[0103] The design method of the negative feedback ultra-wideband low noise amplifier circuit of the application is as follows:

[0104] Step 1, a negative feedback ultra-wideband low noise amplifier circuit structure based on Chebyshev band-pass filter matching network is designed.

[0105] The signal enters the circuit from the input end of the input matching network, the input end of the input matching network is connected with a signal source with an internal resistance of 50 ohms, and the output end is connected with the gate of the high electron mobility transistor, so that the minimum noise matching of the first amplifier is realized, and the working frequency band bandwidth of the overall circuit is widened.

[0106] The second-stage high-gain amplification transistor and the third-stage high-gain amplification transistor are subjected to maximum power matching, so as to improve the gain of the low noise amplifier in the working frequency band, and the output standing wave ratio is optimized through the feedback network.

[0107] The negative feedback network adopts a combination of drain parallel negative feedback and source series inductance negative feedback, overcomes the self-limitation of the transistor through the negative feedback network, compensates the gain roll-off, reduces the gain in the low frequency band, increases the gain in the high frequency band, and optimizes the gain flatness of the overall circuit.

[0108] The input end of the Chebyshev band-pass filter output matching network is connected with the third-stage high-gain amplification transistor, and the output end is connected with a 50 ohm load end.

[0109] Step 2, the drain parallel negative feedback circuit and the source series inductance negative feedback circuit are designed for the negative feedback network. Taking a single-stage negative feedback amplification circuit as an example, the specific circuit design is shown in Figure 2 .

[0110] Among them, Figure 3 The drain parallel negative feedback equivalent circuit schematic diagram is shown in the figure, which sequentially includes a feedback resistor R fb , a gate-source capacitance C gs , a transconductance g m , a gate current i1, a drain current i2, a voltage V1 between the gate and the source, and a voltage V2 between the drain and the source.

[0111] Further, the working principle of the drain parallel negative feedback is further explained:

[0112] The admittance matrix of the equivalent circuit is:

[0113]

[0114] The corresponding S parameter is:

[0115]

[0116]

[0117]

[0118] where Z0 is the characteristic impedance, R fb is the parallel feedback resistance.

[0119] When matched, S 11 = S 22 = 0, the input-output return loss VSWR = 1, at this time, from the formula can be derived

[0120] R fb = g m Z0 2

[0121] Thus,

[0122]

[0123] It is shown that the gain of the parallel negative feedback low noise amplifier is determined by the feedback resistance. By optimizing the resistance tuning to achieve the purpose of controlling the gain flatness.

[0124] Figure 4 The transistor source series inductance negative feedback equivalent circuit diagram is shown, including gate resistance R g , gate-source capacitance C gs and voltage drop V c , inter-electrode transconductance g m , source series inductance L s , voltage between gate and source V g , gate current i g , current between drain and source i s ;

[0125] Further, the relationship between the parameters in the transistor source series inductance negative feedback equivalent circuit is calculated and analyzed:

[0126]

[0127] S = jw

[0128]

[0129] Replace s with jw, and the frequency response of the input impedance is obtained:

[0130]

[0131] The real part and the imaginary part of the impedance are separated

[0132] Z in = R g + R a + j (X ls - X cgs )

[0133] The input impedance of the transistor itself is

[0134] Z in = R g -jX cgs

[0135] When an ideal inductor is connected in series with the source, the input impedance increases R a +jX ls . So that Z in is closer to the optimal reflection coefficient, and the matching performance is greatly improved, so that an ideal inductor is connected in series with the source. As feedback is conducive to simultaneously achieving noise matching and power matching. The present application uses a section of microstrip line instead of an inductor to achieve a compromise between the standing wave ratio, the noise figure, and the amplifier gain.

[0136] Step 3, for the traditional T-type and π-type matching network, only impedance matching is performed around a single frequency point, and the frequency band is narrow. The present application uses the simple structure, wide frequency band, and steep edge characteristics of the Chebyshev filter to design a Chebyshev bandpass filter topology for broadband matching of the low-noise amplifier. Figure 5 As shown,

[0137] The input matching network and the output matching network correspond to the LC part of the left half and the LC part of the right half, respectively, which are sensitive to low frequencies. The input matching network and the output matching network correspond to the LC part of the right half and the LC part of the left half, respectively, which are sensitive to high frequencies. By selecting appropriate parameters, the impedance trajectory is compressed and knotted at the center of the Smith chart, and the broadband matching of the low-noise amplifier is realized. The specific implementation idea is as follows: taking the Chebyshev bandpass filter input matching network as an example,

[0138] Firstly, according to the transmission line theory, when a transmission line is connected from the load end to the source end, the reflection coefficient of the load end will rotate clockwise by an angle of 2 times the electrical length of the transmission line with the characteristic impedance of the transmission line as the center, so that S 11 The center frequency f0 point of the S

[0139] Referring to Figure 6 ,

[0140] In the case that the f0 point in the S 11 curve remains unchanged, the parallel resonant loop in the Chebyshev filter network is used, and the resonant frequency is taken as f0. The present application relates to a higher frequency band, and a microstrip stub is used instead of a lumped parameter element. The total admittance of the parallel resonant loop is

[0141] Y = jY0(tanβl-cotβl)

[0142] Wherein, β is phase constant, l is transmission line geometric length. In order to keep the position of f0 unchanged, the electrical length of the parallel branch microstrip stub is set to 45°. Since the length of the parallel microstrip line is determined in the actual circuit, the electrical length of the parallel microstrip line will be greater than 45° at the high frequency band, and S 11 The curve moves clockwise along the constant-admittance circle. Similarly, the electrical length of the parallel microstrip line will be less than 45° at the low frequency band, and S 11 The curve moves counterclockwise along the constant-admittance circle, so that S 11 The curve is folded inward and knotted.

[0143] In the ADS schematic simulation, the characteristic impedance, electrical length and other parameters are optimized, and S 11 The curve is matched to the specified constant input standing wave ratio circle. Referring to Figure 7 , the Chebyshev band-pass filter matching network is realized to the wideband matching of the ultra-wideband low-noise amplifier.

[0144] Referring to Figures 8-10 , the simulation result diagram of gain, gain flatness, return loss and noise figure of the negative feedback ultra-wideband low-noise amplifier based on the Chebyshev band-pass filter matching network is shown, and in the working frequency band of 2-11GHz, the gain is greater than 30dB, the in-band gain fluctuation is less than 5dB, the return loss is less than -10dB, the front and rear matching is better realized, the in-band and out-of-band is absolutely stable, and the noise figure is less than 1.73dB, which is consistent with the design method described in the application.

[0145] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the application and are not limiting. Although the application has been described in detail through the above preferred examples, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the application.

Claims

1. A design method of a negative feedback ultra-wideband low noise amplifier circuit, characterized by, At least comprising the following steps: Step 1: a negative feedback ultra-wideband low noise amplifier circuit structure based on Chebyshev band-pass filter matching network is designed, wherein at least comprising an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network and an output matching network, wherein the input matching network and the output matching network both adopt Chebyshev band-pass filter network structure; Step 2: A drain parallel negative feedback circuit and a source series inductance negative feedback circuit are designed, wherein the equivalent circuit of the drain parallel negative feedback circuit comprises a feedback resistor , a gate-source capacitance , a transconductance , a gate current , a drain current , a voltage between the gate and the source , and a voltage between the drain and the source ; The admittance matrix of the equivalent circuit is: ； The corresponding S parameter is: ； ； ； wherein is the characteristic impedance, is the parallel feedback resistance; When matched, , input-output return loss VSWR = 1, at this time from the formula can be derived ； Therefore, ； The purpose of controlling gain flatness is achieved by optimizing and tuning the resistance; The equivalent circuit of the transistor source series inductance negative feedback circuit structure comprises in order a gate resistance , a gate-source capacitance and a voltage drop thereof , an interelectrode transconductance , a source series inductance , a voltage between the gate and the source , a gate current and a current between the drain and the source ; Wherein, the relationship between the parameters in the equivalent circuit of the transistor source series inductance negative feedback is calculated and analyzed: ； ； ； With replacing , the frequency response of the input impedance is: ； The real part and the imaginary part of the impedance are separated ； The input impedance of the transistor itself is ； When a perfect inductance is connected in series to the source, the input impedance increases ; making the optimal reflection coefficient closer, the matching performance is greatly improved, so that a perfect inductance is connected in series to the source; A section of microstrip line is used to replace the inductance, and a compromise optimization between the standing wave ratio, the noise figure and the amplifier gain is achieved; Step 3: a Chebyshev band-pass filter topology structure is designed for wideband matching of the low noise amplifier, wherein The input matching network and the output matching network correspond to the LC part of the left half and the LC part of the right half respectively, which are sensitive to low frequency, and the input matching network and the output matching network correspond to the LC part of the right half and the LC part of the left half respectively, which are sensitive to high frequency; By selecting appropriate parameters, the impedance locus is compressed and knotted at the center of the Smith chart, realizing the wideband matching of the low noise amplifier.

2. The design method of a negative feedback ultra-wideband low noise amplifier circuit according to claim 1, characterized in that, Step 3 further comprises the following steps: According to the transmission line theory, when the load end is connected to the source end through a transmission line, the reflection coefficient of the load end will rotate clockwise by an angle of 2 times the electrical length of the transmission line with the characteristic impedance of the transmission line as the center, so that center frequency of the curve the point moves clockwise along the dotted circle to the pure resistance axis of the Smith chart; In making The curve With the parallel resonant circuit in the Chebyshev filter network, the resonant frequency is taken as , the microstrip stub is used instead of the lumped parameter element; the total admittance of the parallel resonant circuit is: ； wherein, is a phase constant, is the geometric length of the transmission line; to keep the position of the curve unchanged, the electrical length of the shunt stub microstrip is set to 45°; since the length of the shunt microstrip in the actual circuit is determined, the electrical length of the shunt microstrip will be greater than 45° at the high frequency band, the curve moves clockwise along the constant-admittance circle; similarly, the electrical length of the shunt microstrip will be less than 45° at the low frequency band, the curve moves counterclockwise along the constant-admittance circle, so that the electrical length of the shunt microstrip at the low frequency band and at the high frequency band the curve is folded inward and knotted; In the ADS schematic simulation, the parameters such as characteristic impedance and electrical length are optimized, and the curve is matched to the specified input standing wave ratio circle to realize the wideband matching of the Chebyshev band-pass filter network to the ultra-wideband low-noise amplifier. The curve is matched to the specified input standing wave ratio circle to realize the wideband matching of the Chebyshev band-pass filter network to the ultra-wideband low-noise amplifier.

3. The negatively fed back ultra-wideband low noise amplifier circuit designed as per claim 1, characterized in that, At least comprising an input matching network, a first amplifier, a second amplifier, a third amplifier, a first negative feedback network, a second negative feedback network, a third negative feedback network and an output matching network, wherein The input matching network is used to match 50 ohm impedance to the minimum noise impedance point of the transistor, so that the power amplifier obtains the minimum noise and at the same time completes the wideband matching of the low noise amplifier; The input end is connected with a signal source, and the output end is connected with the first amplifier, the second amplifier and the third amplifier in turn; Each amplifier is connected with the first negative feedback network, the second negative feedback network and the third negative feedback network respectively; The first amplifier adopts optimal noise matching, which realizes radio frequency wideband matching and low noise amplification in combination with the input matching network; The second amplifier and the third amplifier both adopt maximum power matching, which are used to realize high gain amplification function; The input end of the output matching network is connected with the output end of the third amplifier, which is used to match 50 ohm impedance to the highest gain impedance point of the transistor, so that the power amplifier obtains the best gain and at the same time completes the wideband matching of the low noise amplifier.

4. The negatively fed back UWB low noise amplifier circuit of claim 3, wherein, The input matching network and the output matching network both adopt Chebyshev band-pass filter network structure.

5. The negatively fed back UWB low noise amplifier circuit according to claim 3 or 4, characterized in that, The first negative feedback network, the second negative feedback network and the third negative feedback network all adopt drain parallel negative feedback circuit structure and source series inductance negative feedback circuit structure.

6. The negatively fed back UWB low noise amplifier circuit of claim 5, wherein, The first amplifier, the second amplifier and the third amplifier all adopt HEMT device.

7. The negatively fed back UWB low noise amplifier circuit of claim 5, wherein, The equivalent circuit of the drain parallel negative feedback circuit structure comprises feedback resistors in sequence , a gate-source capacitance , a transconductance , a gate current , a drain current , a voltage between the gate and the source , a voltage between the drain and the source ; The admittance matrix of the equivalent circuit is: ； The corresponding S parameter is: ； ； ； wherein is a characteristic impedance, is a parallel feedback resistance; When matched, , input-output return loss VSWR = 1, from which it follows that: ； Therefore, ； The purpose of controlling gain flatness is achieved by optimizing and tuning the resistance.

8. The negatively fed back UWB low noise amplifier circuit of claim 5, wherein, The equivalent circuit of the source series inductance negative feedback circuit structure comprises in order a gate resistance , a gate-source capacitance and its voltage drop , an interelectrode transconductance , a source series inductance , a voltage between the gate and the source , a gate current , and a current between the drain and the source ; Wherein: ； ； ； With replacing , the frequency response of the input impedance is: ； The real part and the imaginary part of the impedance are separated: ； The input impedance of the transistor itself is: ； Using a section of microstrip line instead of an inductor for the feedback facilitates simultaneous noise and power matching.

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