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Circuit and method for cancelling preceding stage thermal noise of low noise amplifier

A low-noise amplifier and thermal noise technology, which is applied in the direction of improving the amplifier to reduce the influence of noise, and can solve problems such as difficult to achieve noise matching and conjugate matching at the same time

Active Publication Date: 2012-07-04
ZHEJIANG UNIV
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Problems solved by technology

However, since this method is mainly based on directly matching the input impedance of the circuit without in-depth study of the physical mechanism of matching, it is difficult for the traditional method to achieve noise matching and conjugate matching at the same time, especially in the trade-off relationship between bandwidth and noise. limitation

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  • Circuit and method for cancelling preceding stage thermal noise of low noise amplifier
  • Circuit and method for cancelling preceding stage thermal noise of low noise amplifier

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Embodiment Construction

[0016] The present invention will be further described below in conjunction with accompanying drawing.

[0017] like figure 1 As shown, a circuit for eliminating thermal noise in the front stage of a low-noise amplifier includes a DC power supply Vcc, a first inductor L1, a second inductor L2, a first resistor R1, a second resistor R2, a third resistor R3, and a first transistor Q1, the second transistor Q2, the third transistor Q3, the fourth transistor Q4, the first capacitor C1, the second capacitor C2, and the third capacitor C3; one end of the first inductor L1 is the input end, connected to the signal source, and the other end of the first inductor L1 One end is connected to one end of the first capacitor C1 and the base of the first transistor Q1; the other end of the first capacitor C1 is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to one end of the second resistor R2, one end of the second capacitor C2, The colle...

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Abstract

The invention discloses a circuit and a method for cancelling the preceding stage thermal noise of low noise amplifier. By the traditional method, noise matching and conjugation matching are difficultly achieved at the same time, and particularly the compromise relationship of bandwidth and noise has certain limit. The circuit comprises a direct current power supply Vcc, a first inductor L1, a second inductor L2, a first resistor R1, a second resistor R2, a third resistor R3, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a first capacitor C1, a second capacitor C2 and a third capacitor C3. By the method, the preceding state thermal noise of the amplifier is detected through a thermal noise cancelling technology, and is added and cancelled by two signal paths which have opposite gains after being finely adjusted. By the circuit and the method, the preceding stage thermal noise is completely cancelled, the compromise relationship of the noise matching and the conjugation matching is not required to be considered in the circuit, and the wideband low noise performance is relatively easily obtained.

Description

technical field [0001] The invention belongs to the technical field of radio frequency circuits, and in particular relates to a circuit and method for eliminating thermal noise in the pre-stage of a low-noise amplifier. Background technique [0002] At present, in order to improve the noise and broadband performance of low-noise amplifiers, the three structures of Source Inductive Degeneration, Common Gate, and Feedback are mainly used to change the output impedance. Impedance matching for output noise matching. However, since this method is mainly based on directly matching the input impedance of the circuit without in-depth study of the physical mechanism of matching, it is difficult for the traditional method to achieve noise matching and conjugate matching at the same time, especially in the trade-off relationship between bandwidth and noise. limitation. [0003] At the same time, broadband and ultra-wideband low noise amplifiers have been extensively studied in recent...

Claims

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Application Information

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IPC IPC(8): H03F1/26
Inventor 虞小鹏南超州贾梦楠
Owner ZHEJIANG UNIV
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