Automatic gain control circuit and its automatic attenuating circuit and variable attenuater

Abstract

An automatic attenuation circuit consists of variable attenuator for attenuating input signal and for deciding attenuation amount of input signal according to the second control signal, signal detector for detecting output of variable attenuator and for outputting the first control signal in direct ratio to input signal, reversed buffer coupled to variable attenuator and signal detector for reversing the first control signal so as to output the second control signal.

Description

technical field [0001] The invention relates to a controllable gain circuit, in particular to an automatic gain control circuit, an automatic attenuation circuit and a variable attenuator. Background technique [0002] Automatic gain control circuits are often used in transmission systems. In different environments and conditions, the input signal obtained by the transmission system is often unstable, so the automatic gain control circuit is required to automatically change different system gains to complete stable transmission work. The traditional automatic gain control circuit is to add an automatic attenuation circuit at the output of the amplifier, such as Figure 1A shown. [0003] Figure 1A Is the traditional automatic gain control circuit block diagram. Please refer to Figure 1A The unstable input signal Vin is first amplified by the amplifier 110, and then the automatic attenuation circuit composed of the variable attenuator 120 and the signal detector 130 appro...

AI Technical Summary

Problems solved by technology

[0006] However, under certain design requirements, if the control signal output by the signal detector increases as the input signal increases, the traditional automatic attenuation circuit will not be applicable

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