Low-noise amplifier based on post-distortion technology

Abstract

The invention discloses a low noise amplifier based on a post-distortion technology, which is characterized by comprising a low noise circuit, a post-distortion circuit and an active bias circuit, the low-noise circuit comprises an amplifying circuit of which the topology is of a common-source or common-source and common-gate structure; the low-noise circuit is used for amplifying received signals, the post-distortion circuit provides phase and gain for the low-noise circuit for nonlinear compensation so as to realize linear output of the low-noise circuit, and the active bias circuit provides voltage for the low-noise amplifying circuit and provides control voltage for a control end of the distortion circuit. According to the invention, both the linearity and noise coefficient of the circuit can be ensured, and the robustness of the circuit is improved.

Description

Technical Field

[0001] The invention belongs to the field of integrated circuit design, and in particular relates to a low-noise amplifier based on post-distortion technology. Background Art

[0002] With the development of communication systems, complex debugging methods have led to a gradual increase in the peak-to-average ratio requirements of signals, which requires the system's receiver to have better dynamic range and sensitivity indicators.

[0003] Receivers are usually used to process weak signals. The noise figure of the low noise amplifier (LNA) in the receiver determines the minimum useful signal power that the receiver can detect in the noise, and also guarantees the sensitivity index of the receiver. At this time, the LNA is in a small signal state and can be considered as a linear system. The useful signal will be linearly amplified, but as the interference signals of different channels increase, this will cause the amplitude and phase of the LNA to be in a nonlinear state. The multi-order nonlinear parameters generated will affect the communication quality of the receiving system. A high-linearity LNA will give the receiver a larger dynamic range. The linearity index can be defined from the perspective of amplitude and phase using the AM-AM / AM-PM index. Therefore, as a key component of the receiving system, the noise figure and linearity of the low noise amplifier (LNA) are crucial to the communication quality.

[0004] In the design of low-noise amplifiers, optimizing linearity while ensuring a good noise figure has always been a design difficulty. At present, there are many technical means to improve the linearity index of low-noise amplifiers. The optimal gate bias technology selects the appropriate gate bias point of the die to optimize the linearity, but this method will sacrifice the robustness and noise performance of the chip; the pre-distortion technology can significantly improve the linearity by compensating for amplitude and phase distortion, but the pre-distortion technology will be placed at the input end, which will have a too obvious effect on noise deterioration; the derivative superposition technology uses the nonlinear parameters of multiple groups of parallel die to offset the multi-order derivatives of the main working die. This method can reduce the deterioration of the noise figure, but the linearity improvement brought by the high redundancy design is limited; how to use simple and effective linear optimization technology without deteriorating the noise has become an urgent problem to be solved. Summary of the invention

[0005] Purpose of the invention: In order to solve the problems existing in the above-mentioned prior art, the present invention provides a low-noise amplification based on post-distortion technology.

[0006] Technical solution: The present invention discloses a low-noise amplifier based on post-distortion technology, including a low-noise circuit, a post-distortion circuit and an active bias circuit; the low-noise circuit includes an amplifier circuit with a topology of a common source stage or a common source common gate structure;

[0007] The low-noise circuit is used to amplify the received signal, the post-distortion circuit provides phase and gain for the low-noise circuit for nonlinear compensation, thereby achieving a linear output of the low-noise circuit, and the active bias circuit provides voltage for the low-noise amplifier circuit and provides a control voltage for the control end of the distortion circuit.

[0008] Furthermore, the low-noise circuit includes a first transistor, first to third inductors, first to third capacitors and a grounding resistor, one end of the first capacitor is an input end, and the other end is a gate voltage input end, and the other end of the first capacitor is connected to the gate of the first transistor through the first inductor, the drain of the first transistor is connected to one end of the third inductor, and the other end of the third inductor serves as a drain voltage input end; and the other end of the third inductor is connected to one end of the second capacitor, and the other end of the second capacitor serves as an output end of the low-noise circuit, the source of the first transistor is connected to one end of the second inductor, and the other end of the second inductor is connected to the ground in parallel with the third capacitor through the grounding resistor.

[0009] Furthermore, the active bias circuit provides a gate voltage and a drain voltage for the low noise amplifier circuit.

[0010] Furthermore, the active bias circuit includes first to fourth resistors and third and fourth transistors, the gate of the third transistor is connected to the drain of the third transistor through the first resistor, the source of the third transistor is grounded, the drain is connected to one end of the second resistor, the drain of the third transistor serves as the output end of the VG voltage, and provides a gate voltage for the low-noise circuit; the other end of the second resistor is connected to the input voltage VD and one end of the third resistor, the input voltage VD is used as the drain voltage of the low-noise circuit, the other end of the third resistor is connected to the gate of the fourth transistor, the gate of the fourth transistor serves as the output end of the VC voltage to provide a control voltage for the post-distortion circuit; the gate of the fourth transistor is connected to the drain of the fourth transistor through the fourth resistor, and the source of the fourth transistor is grounded.

[0011] Furthermore, it also includes a fourth inductor, a fifth inductor, a fourth and fifth capacitors and a fifth resistor; the VG voltage output by the active bias circuit is connected to one end of the fourth inductor and one end of the fourth capacitor, the other end of the fourth inductor is connected to the gate voltage input end of the low-noise circuit, the other end of the fourth capacitor is grounded, the VD voltage output by the active bias circuit is connected to one end of the fifth inductor and one end of the fifth capacitor, one end of the fifth inductor is connected to the output end of the low-noise circuit, and the other end of the fifth capacitor is grounded; the VC voltage output by the active bias circuit provides a control voltage for the post-distortion circuit through the fifth resistor.

[0012] Further, the post-distortion circuit includes a second transistor, a sixth resistor, a negative feedback resistor and a negative feedback capacitor; one end of the sixth resistor is connected to the low-noise circuit, and the other end is connected to one end of the negative feedback resistor and the source of the second transistor, the other end of the negative feedback resistor is connected to one end of the negative feedback capacitor, and the other end of the negative feedback capacitor is connected to the drain of the second transistor, the drain of the second transistor is the output end of the post-distortion circuit, and the gate of the second transistor is connected to the active bias circuit as the control end of the post-distortion circuit.

[0013] Furthermore, a sixth capacitor is included, one end of the sixth capacitor is connected to the post-distortion circuit, and the other end serves as an output end of the low noise amplifier.

[0014] Beneficial effects:

[0015] 1. In the present invention, since the post-distortion circuit is placed at the output end of the low-noise circuit, the loss of the post-distortion circuit has limited effect on the noise of the overall circuit, thereby ensuring that both the linearity and the noise coefficient of the circuit are achieved.

[0016] 2. The power-on control of the low-noise amplifier circuit and the post-distortion circuit of the present invention can be provided by a single power supply input of the active bias circuit. The power-on terminal is a single universal port when in use, which is highly versatile and easy to use.

[0017] 3. The present invention adopts the method of connecting the control tube core and the RC negative feedback circuit in parallel to realize the adjustment of the linearization technology. The phase and gain compensation of different amplifiers can be realized by changing different combinations of the control voltage and the negative feedback RC value, and the compatibility is strong.

[0018] 4. The current mirror topology of the active bias circuit of the present invention combined with the source parallel RC structure of the low-noise amplifier circuit can effectively reduce the degree of linearity degradation caused by process discreteness, and the circuit has good robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a principle block diagram of a low noise amplifier based on post-distortion technology of the present invention;

[0020] Figure 2 The present invention is a circuit diagram of a low noise amplifier based on post-distortion technology;

[0021] Figure 3 It is a schematic diagram of the post-distortion technology of the low noise amplifier based on the post-distortion technology of the present invention;

[0022] Figure 4 is a schematic diagram of a post-distortion circuit in the present invention;

[0023] Figure 5 It is the amplitude compensation curve diagram of the post-distortion circuit under different control voltages VC;

[0024] Figure 6 It is a phase compensation curve diagram of the post-distortion circuit under different control voltages VC. DETAILED DESCRIPTION

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] like Figure 1 As shown, the present invention provides a low-noise circuit based on post-distortion technology, including a low-noise circuit, a post-distortion circuit, and an active bias circuit.

[0027] The low noise circuit comprises a class A amplifier circuit, the topology of which is a common source or common source common gate structure, and is used to achieve performance indicators of low noise and high gain.

[0028] The post-distortion circuit includes b control tube cores and c passive devices of resistors and capacitors. The tube cores and passive devices can be connected in series or in parallel to increase the nonlinearity, and different nonlinear compensations can be achieved under different control gate voltages.

[0029] The active bias circuit includes one group of input ports and three groups of output ports. The input port is an external power supply voltage. One end of the output port is connected to the control port of the post-distortion circuit, and the other two ends are power-on ports of the low-noise circuit. The topology adopted is a current mirror structure, so that the level of the output port has high stability.

[0030] Figure 2 In the preferred embodiment of the present invention, the transistor M1 with a common source, the inductor LS1, the inductor LG1, the inductor LD1, the capacitor C1 and the capacitor C2 matched therewith constitute the main amplification circuit of the low noise amplifier; Figure 3 , Figure 4 As shown, the common-gate transistor M2, the resistor RS2 connected to the ground by the source electrode thereof, the negative feedback resistor RFD, and the RC negative feedback circuit of the negative feedback capacitor CFD constitute a post-distortion circuit; the transistor M3, the resistor R1, and the resistor R2 provide the gate voltage VG of the low-noise amplifier; the transistor M4, the resistor R3, and the resistor R4 provide the control voltage VC of the post-distortion circuit, and VD is directly given by the input port of the active bias circuit.

[0031] In this embodiment, since the post-distortion circuit is placed at the output end of the low-noise circuit, the following noise cascade formula is obtained:

[0032]

[0033] In the formula, NF represents the noise factor of the low noise amplifier, NF1 represents the noise factor of the low noise circuit, NF2 is the noise loss of the post-distortion circuit, and G1 represents the gain of the low noise circuit. Since the gain of G1 is more than 20 times, the loss of the post-distortion circuit has limited impact on the noise of the overall circuit, which can ensure that the linearity and noise factor of the circuit are both achieved.

[0034] The inductor LS1 of the low-noise circuit is connected in parallel to the ground structure through the capacitor CS1 and the resistor RS1, which can effectively reduce the impact of the threshold change of M1 caused by process discreteness and increase the robustness of the circuit.

[0035] The low noise amplifier circuit is connected to the VG output port of the active bias circuit through the inductor L1 and the ground capacitor COV1, and is connected to the VD output port of the active bias circuit through the inductor L2 and the ground capacitor COV2 to prevent crosstalk between the low noise amplifier circuit and the active bias circuit; the post-distortion circuit is connected to the VC output port of the active bias circuit through R5 to prevent crosstalk between the post-distortion circuit and the active bias circuit.

[0036] The active bias circuit is a current mirror structure, adopts a single power supply input control method, and the output provides a gate voltage VG of the low noise amplifier circuit and a control voltage VC of the post-distortion circuit, which provides effective control over the influence of process fluctuations and increases the robustness of the overall circuit.

[0037] The working principle of the present invention is:

[0038] When the input port RFin of the low-noise circuit is a low-power signal, the low-noise circuit is in a small-signal working state and can be linearly amplified, and the post-distortion circuit is also in linear operation with certain losses. At this time, the overall circuit is a low-noise amplifier with normal output; but as the signal power received by the input port RFin increases, the low-noise circuit will be in a large-signal working state and gain and phase compression will occur, and the post-distortion circuit will provide an opposite gain and phase nonlinearity at this time. The superposition of the two can ensure that the entire low-noise amplifier chip is still in a linear working state.

[0039] Since different low-noise circuits are designed with different die sizes and topologies, their gain compression and phase compression values ​​will be different. The nonlinear adjustment of the amplitude and phase by the post-distortion circuit under different control voltages VC is as follows: Figure 5 and Figure 6 shown.

[0040] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A low noise amplifier based on post-distortion technology, characterized in that: It includes a low-noise circuit, a post-distortion circuit and an active bias circuit; the low-noise circuit includes an amplifier circuit with a common-source or common-source common-gate topology; The low-noise circuit is used to amplify the received signal, the post-distortion circuit provides phase and gain for the low-noise circuit for nonlinear compensation, thereby achieving a linear output of the low-noise circuit, and the active bias circuit provides voltage for the low-noise amplifier circuit and provides a control voltage for the control end of the distortion circuit.

2. The low noise amplifier based on post-distortion technology according to claim 1, characterized in that: The low-noise circuit includes a first transistor, first to third inductors, first to third capacitors and a grounding resistor, one end of the first capacitor is an input end, and the other end is a gate voltage input end, and the other end of the first capacitor is connected to the gate of the first transistor through the first inductor, the drain of the first transistor is connected to one end of the third inductor, and the other end of the third inductor serves as a drain voltage input end; and the other end of the third inductor is connected to one end of the second capacitor, and the other end of the second capacitor serves as an output end of the low-noise circuit, the source of the first transistor is connected to one end of the second inductor, and the other end of the second inductor is connected to the ground in parallel with the third capacitor through the grounding resistor.

3. The low noise amplifier based on post-distortion technology according to claim 2, characterized in that: The active bias circuit provides a gate voltage and a drain voltage for the low noise amplifier circuit.

4. The low noise amplifier based on post-distortion technology according to claim 2, characterized in that: The active bias circuit includes first to fourth resistors and third and fourth transistors. The gate of the third transistor is connected to the drain of the third transistor through the first resistor, the source of the third transistor is grounded, and the drain is connected to one end of the second resistor. The drain of the third transistor serves as an output end of the VG voltage to provide a gate voltage for the low-noise circuit; the other end of the second resistor is connected to the input voltage VD and one end of the third resistor, and the input voltage VD is used as the drain voltage of the low-noise circuit. The other end of the third resistor is connected to the gate of the fourth transistor. The gate of the fourth transistor serves as an output end of the VC voltage to provide a control voltage for the post-distortion circuit; the gate of the fourth transistor is connected to the drain of the fourth transistor through the fourth resistor, and the source of the fourth transistor is grounded.

5. The low noise amplifier based on post-distortion technology according to claim 4, characterized in that: It also includes a fourth inductor, a fifth inductor, a fourth and fifth capacitors and a fifth resistor; the VG voltage output by the active bias circuit is connected to one end of the fourth inductor and one end of the fourth capacitor, the other end of the fourth inductor is connected to the gate voltage input end of the low noise circuit, the other end of the fourth capacitor is grounded, the VD voltage output by the active bias circuit is connected to one end of the fifth inductor and one end of the fifth capacitor, one end of the fifth inductor is connected to the output end of the low noise circuit, and the other end of the fifth capacitor is grounded; the VC voltage output by the active bias circuit provides a control voltage for the post-distortion circuit through the fifth resistor.

6. The low noise amplifier based on post-distortion technology according to claim 1, characterized in that: The post-distortion circuit includes a second transistor, a sixth resistor, a negative feedback resistor and a negative feedback capacitor; one end of the sixth resistor is connected to the low-noise circuit, and the other end is connected to one end of the negative feedback resistor and the source of the second transistor, the other end of the negative feedback resistor is connected to one end of the negative feedback capacitor, and the other end of the negative feedback capacitor is connected to the drain of the second transistor, the drain of the second transistor is the output end of the post-distortion circuit, and the gate of the second transistor is connected to the active bias circuit as the control end of the post-distortion circuit.

7. The low noise amplifier based on post-distortion technology according to claim 1, characterized in that: It also includes a sixth capacitor, one end of which is connected to the post-distortion circuit, and the other end of which serves as an output end of the low noise amplifier.

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