阅读说明：本技术 基于无源Balun的宽带高增益高线性度低噪声放大器 (Broadband high-gain high-linearity low-noise amplifier based on passive Balun ) 是由 李智群 王晓伟 李振南 陈伯凡 于 2021-08-11 设计创作，主要内容包括：本发明公开了一种基于无源Balun的宽带高增益高线性度低噪声放大器,设有输入匹配单元、放大单元、反馈单元以及负载单元。射频输入单端信号连接输入匹配单元,输入匹配单元的输出连接放大单元,放大单元连接到反馈单元输入,反馈单元连接到输入匹配单元的输入,放大单元同时连接到输出负载单元,输出负载单元输出射频双端射频信号。本发明能在保证宽带特性的基础上,降低放大器的噪声,提高放大器的增益和线性度,并且实现单端信号输入,双端信号输出的有益效果。(The invention discloses a broadband high-gain high-linearity low-noise amplifier based on passive Balun, which is provided with an input matching unit, an amplifying unit, a feedback unit and a load unit. The radio frequency input single-ended signal is connected with the input matching unit, the output of the input matching unit is connected with the amplifying unit, the amplifying unit is connected with the input of the feedback unit, the feedback unit is connected with the input of the input matching unit, the amplifying unit is simultaneously connected with the output load unit, and the output load unit outputs a radio frequency double-ended radio frequency signal. The invention can reduce the noise of the amplifier, improve the gain and the linearity of the amplifier and realize the beneficial effects of single-end signal input and double-end signal output on the basis of ensuring the broadband characteristic.)

1. A broadband high-gain high-linearity low-noise amplifier based on passive Balun is characterized by comprising an input matching unit (1), an amplifying unit (2), a feedback unit (3) and a load unit (4);

the radio frequency input single-ended signal is connected with the input matching unit (1), the output of the input matching unit (1) is connected with the amplifying unit (2), the amplifying unit (2) is connected with the input of the feedback unit (3), the feedback unit (3) is connected with the input of the input matching unit (1), the amplifying unit (2) is simultaneously connected with the output load unit (4), and the output load unit (4) outputs a radio frequency double-ended radio frequency signal.

2. The passive Balun-based broadband high-gain high-linearity low-noise amplifier according to claim 1, wherein the input matching unit (1) comprises an inductance L1 and an inductance L2;

the amplifying unit (2) comprises a transistor M1 and a transistor M2;

the feedback unit (3) comprises a resistor R1 and a capacitor C1;

the load unit comprises capacitors C2 and C3, a resistor R2 and a transformer T1;

the transformer T1 comprises inductors L3 and L4;

the radio frequency input signal is respectively connected with an inductor L1 of the input matching unit (1) and a capacitor C1 in the feedback unit (3), the inductor L1 is connected with the gate of a transistor M1 in the amplifying unit (2), the source of the transistor M1 is connected with an inductor L2, the inductor L2 is grounded, the drain of the transistor M1 is connected with the source of the transistor M2, the gate of a transistor M1 is connected with a bias voltage VG, the gate of the transistor M2 is connected with a power supply voltage, the bias voltage of the transistor M2 is provided by the power supply voltage, the drain of the transistor M2 is respectively connected with a resistor R1 in the feedback unit (3), the capacitor C2 in the load unit (4) and the inductor L3 in the transformer T1, the resistor R1 in the feedback unit (3) is connected with the capacitor C1, the capacitor C2 in the load unit and the inductor L3 in the transformer T1 are connected with the power supply voltage, and the inductor L4 in the transformer T1, the capacitor C3 and the resistor R2 are connected in parallel and are connected with the output radio-frequency signal at the same time.

3. The passive Balun-based broadband high-gain high-linearity low-noise amplifier according to claim 2, wherein the inductor L1 is provided with a radial shielding layer to increase the Q value and reduce the loss of an input signal on the inductor L1.

4. The passive Balun-based broadband high-gain high-linearity low-noise amplifier according to claim 2, wherein the transistor M1 adopts four identical transistors connected in parallel to reduce the gate resistance of the transistor.

Technical Field

The invention belongs to the field of radio frequency integrated circuits, and particularly relates to a high-linearity low-noise amplifier based on passive Balun broadband matching.

Background

In a communication system, it is often necessary to initially amplify a signal in a certain frequency band using a circuit called a low noise amplifier as a first stage of a receiving chain, and to introduce low noise while ensuring sufficient gain. Low noise amplifiers are very critical modules in wireless receivers, and are designed to meet various design requirements, such as: low noise, low power consumption, high gain, high linearity and large bandwidth. Because some design indexes have contradictions, the design is difficult to be considered completely, and compromise is required or some technical means are required.

The traditional broadband low noise amplifier usually adopts a common-gate amplifier or a resistance feedback common-source amplifier, wherein in order to meet the broadband input matching, the transconductance of a transistor is limited, and the noise performance and the gain performance of the amplifier are poor. As shown in fig. 1, in the conventional resistive feedback common-source amplifier circuit, a radio frequency signal is input from a gate of a transistor M1, a drain of a transistor M1 is connected to a source of a transistor M2, and a drain of a transistor M2 is used as an output terminal of the signal and is also fed back to a gate of a transistor M1 through a resistor R1 and a capacitor C1. The wide-band 50 omega input matching can be realized by adjusting the transconductance of the transistor M1 and the feedback resistor R1, and different gains can be obtained by adjusting the load resistor R2. The structure has a wide input bandwidth and a gain bandwidth, and simultaneously has a certain gain, but the traditional resistance feedback common-source amplifier has the following disadvantages:

the first is low gain, and in order to satisfy broadband input matching, the conventional resistive feedback common-source amplifier needs a relatively small feedback resistance value, which results in strong negative feedback, and the transconductance of the transistor M1 is limited, and the gain is low.

Secondly, the noise performance is poor, the feedback resistor causes the gain of the common-source transistor to be reduced, the noise introduced by the common-gate transistor and the load resistor is increased, and the feedback resistor introduces larger noise, so that the noise performance of the traditional resistor feedback common-source amplifier is poor.

Thirdly, the linearity is poor, and in order to ensure a large gain bandwidth, a resistor is used as a load in the conventional resistor feedback common-source amplifier, and the resistor consumes a part of power supply voltage, so that the linearity of the amplifier is poor.

And fourthly, the traditional resistance feedback common-source amplifier is single-ended signal input and single-ended signal output, the current frequency mixer mostly takes a differential signal input structure as a main structure, and the traditional resistance feedback common-source amplifier is not compatible with the frequency mixer with differential signal input.

Disclosure of Invention

The invention aims to provide a broadband high-gain high-linearity low-noise amplifier based on passive Balun, which can reduce the noise of the amplifier, improve the gain and linearity of the amplifier and realize single-ended signal input and double-ended signal output on the basis of ensuring the broadband characteristic.

In order to solve the technical problems, the specific technical scheme of the invention is as follows:

a broadband high-gain high-linearity low-noise amplifier based on passive Balun comprises an input matching unit, an amplifying unit, a feedback unit and a load unit;

the radio frequency input single-ended signal is connected with the input matching unit, the output of the input matching unit is connected with the amplifying unit, the amplifying unit is connected with the input of the feedback unit, the feedback unit is connected with the input of the input matching unit, the amplifying unit is simultaneously connected with the output load unit, and the output load unit outputs a radio frequency double-ended radio frequency signal.

Further, the input matching unit comprises an inductor L1 and an inductor L2;

the amplifying unit includes a transistor M1 and a transistor M2;

the feedback unit comprises a resistor R1 and a capacitor C1;

the load unit comprises capacitors C2 and C3, a resistor R2 and a transformer T1;

the transformer T1 comprises inductors L3 and L4;

the radio frequency input signal is respectively connected with an inductor L1 in the input matching unit and a capacitor C1 in the feedback unit, an inductor L1 is connected with the gate of a transistor M1 in the amplifying unit, the source of the transistor M1 is connected with an inductor L2, an inductor L2 is grounded, the drain of the transistor M1 is connected with the source of the transistor M2, the gate of a transistor M1 is connected with a bias voltage VG, the gate of the transistor M2 is connected with a power supply voltage, the bias voltage of the transistor M2 is provided by the power supply voltage, the drain of the transistor M2 is respectively connected with a resistor R1 in the feedback unit, a capacitor C2 in the load unit and an inductor L3 in a transformer T1, a resistor R1 in the feedback unit is connected with a capacitor C1, a capacitor C2 in the load unit and an inductor L3 in the transformer T1 are connected with the power supply voltage, and an inductor L4 in the transformer T1 is connected with a capacitor C3 and a resistor R2 in parallel and is connected with the radio frequency output signal.

Furthermore, the inductor L1 is provided with a radial shielding layer to increase the Q value and reduce the loss of the input signal on the inductor L1.

Further, the transistor M1 uses four identical transistors connected in parallel to reduce the gate resistance of the transistor.

The broadband high-gain high-linearity low-noise amplifier based on the passive Balun has the following advantages:

(1) according to the invention, the passive Balun is introduced to convert the single-ended signal into the differential signal, and two load peak values are formed by utilizing the resonance of two inductors of the passive Balun and a capacitor in the load unit, so that the gain bandwidth and the input matching bandwidth are greatly improved;

(2) the passive Balun is introduced to participate in broadband matching, and the resistance value in the feedback unit can be 1-2 k omega, so that compared with a traditional common source amplifier with a feedback resistor, the broadband wide-band amplifier is larger in feedback resistance value, lower in negative feedback strength and higher in gain;

(3) according to the invention, two inductors in the input matching unit are introduced to participate in matching, the transconductance of a common source transistor in the amplifying unit can be adjusted at will so as to obtain the optimal noise performance, the noise introduced by a larger feedback resistor is lower, and compared with the traditional amplifier with resistor feedback, the noise coefficient is greatly reduced;

(4) the invention only has two active devices, introduces few nonlinear factors, adopts a resistance feedback structure to improve the nonlinear performance, and has higher linearity compared with the traditional low-noise amplifier with resistance feedback by adopting Balun as a load;

(5) the broadband high-gain high-linearity low-noise amplifier based on the passive Balun can greatly improve the matching and gain bandwidth, reduce the noise coefficient, improve the voltage gain and the linearity, can be flexibly applied to low, medium and high frequency bands by configuring the parameters of an inductor, a capacitor and a transformer, is simple in design and has good noise and matching performance.

Drawings

FIG. 1 is a circuit schematic of a conventional resistive feedback common source amplifier;

FIG. 2 is a circuit block diagram of the low noise amplifier of the present invention;

FIG. 3 is a circuit schematic of the low noise amplifier of the present invention;

FIG. 4 is an input return loss curve of the low noise amplifier of the present invention;

FIG. 5 is a voltage gain curve for the low noise amplifier of the present invention;

fig. 6 is a graph of the noise figure of the low noise amplifier of the present invention.

The notation in the figure is: 1. an input matching unit; 2. an amplifying unit; 3. a feedback unit; 4. a load unit.

Detailed Description

For better understanding of the purpose, structure and function of the present invention, the following describes a broadband high-gain high-linearity low-noise amplifier based on passive Balun in detail with reference to the accompanying drawings.

As shown in fig. 2, the present invention is provided with an input matching unit 1, an amplifying unit 2, a feedback unit 3, and a load unit 4. The radio frequency input single-ended signal is connected with the input matching unit 1, the output of the input matching unit 1 is connected with the amplifying unit, the amplifying unit 2 is connected with the input of the feedback unit 3, the feedback unit 3 is connected with the input of the input matching unit 1, the amplifying unit 2 is simultaneously connected with the output load unit 4, and the output load unit 4 outputs a radio frequency double-ended radio frequency signal.

As shown in fig. 3, the rf input signal is amplified by the amplifying unit 2 through the input matching unit 1, a part of the amplified signal is fed to the input signal through the feedback unit 3, and the other part of the amplified signal is finally output as the rf output signal through the load unit 4. Wherein: the matching unit 1 is provided with inductors L1 and L2; the amplifying unit 2 is provided with NMOS tubes M1 and M2; the feedback unit 3 is provided with a resistor R1 and a capacitor C1; the load unit 4 is provided with capacitors C2 and C3, a resistor R2 and a transformer T1, wherein the transformer T1 includes inductors L3 and L4. The connection relationship of the circuit is as follows:

the radio frequency input signal is respectively connected with an inductor L1 in the input matching unit 1 and a capacitor C1 in the feedback unit 3, an inductor L1 is connected with the gate of a transistor M1 in the amplifying unit 2, the source of the transistor M1 is connected with an inductor L2, an inductor L2 is grounded, the drain of the transistor M1 is connected with the source of the transistor M2, the gate of a transistor M1 is connected with a bias voltage VG, the gate of the transistor M2 is connected with a power supply voltage, the bias voltage of the transistor M2 is provided by the power supply voltage, the drain of the transistor M2 is respectively connected with a resistor R1 in the feedback unit 3, a capacitor C2 in the load unit 4 and an inductor L3 in the transformer T1, a resistor R1 in the feedback unit 3 is connected with a capacitor C1, a capacitor C2 in the load unit and an inductor L3 in the transformer T1 are connected with the power supply voltage, and an inductor L4 and a capacitor C3 and a resistor R2 in the transformer T1 are connected in parallel with the output radio frequency signal. According to the invention, the inductor L1 and the inductor L2 of the input matching unit are introduced, the matching of input 50 omega is realized by matching with the transistor M1, and the input matching can be realized under the transconductance of different transistors M1 by adjusting the parameters of the inductor L1 and the inductor L2, as can be seen from the reference of FIG. 4, the input return loss (S11) of the invention is less than-10 dB within the bandwidth of 2.3-6.3 GHz.

The transconductance of the transistor M1 is regulated and controlled to enable the low noise amplifier of the invention to obtain the optimal noise coefficient performance, the inductor L1 is provided with a radial shielding layer to increase the Q value, reduce the loss of an input signal on the inductor L1 and reduce the noise coefficient, the transistor M1 adopts four same transistors which are connected in parallel to reduce the grid resistance of the transistor, reduce the loss of the input signal and improve the noise performance, as can be seen from referring to FIG. 6, FIG. 6 is a noise coefficient (NF) curve of the low noise amplifier of the invention, and the noise coefficient of the invention is less than 1.48dB within 6 GHz.

In the load unit 4, the on-chip passive Balun is introduced as a load, an input single-ended signal is converted into a double end on the chip, and an inductor of the transformer is connected between a power supply voltage and the drain electrode of the transistor M2.

A capacitor C2 in the load unit 4 is in parallel resonance with an inductor L3 in a transformer T1 to form a load peak value, a capacitor C3 is in parallel resonance with an inductor L4 in a transformer T1 to form another load peak value, parameters of capacitors C2 and C3 and inductors L3 and L4 are reasonably adjusted, the two parallel resonance peak values are respectively placed in high and low frequency bands, Gain bandwidth can be expanded, and flatter Gain performance can be realized in a band, referring to fig. 5, fig. 5 is a Voltage Gain (Voltage Gain) curve of the low noise amplifier of the invention, the Voltage Gain of the invention is about 24dB, and the Gain bandwidth is 2-6.4 GHz. The passive Balun can be flexibly adjusted according to the required bandwidth and gain requirements, a vertical coupling or side coupling Balun structure can be adopted, and only the coupling coefficient and the inductance value of the transformer are required to meet the bandwidth and gain requirements. Resistor R2 can reduce the transformer inductance Q value to avoid uneven in-band gain caused by too high a resonant peak.

The low-noise amplifier designed by the invention works under the voltage of a 1V power supply, the 3dB bandwidth of the gain of the low-noise amplifier is 2-6.4 GHz, the voltage gain is about 24dB, and the in-band noise coefficient is about 1.31-1.57 dB. The bandwidth, the gain and the noise performance of the low-noise amplifier are far superior to those of the traditional low-noise amplifier with a common-gate structure and a resistance feedback common-source low-noise amplifier.

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.