Automatic gain control circuit

Abstract

An automatic gain control circuit for controlling the gain of a variable gain amplifier block includes a count control signal generating block, an up-down counter, a gain control signal generating block, and a downcount clock signal generating block. The up-down counter upcounts an upcount clock signal or downcounts a downcount clock signal according to a count control signal generated by the count control signal generating block. The gain control signal generating block generates a gain control signal corresponding to a count value of the up-down counter. The downcount clock signal generating block generates a downcount clock signal whose frequency corresponds to the count value of the up-down counter. Correspondingly, an automatic gain adjustable circuit with more excellent in audio can be realized without using integral circuit of the capacitor.

Description

technical field [0001] The present invention relates to an automatic gain control circuit for controlling the gain of a variable gain amplifying circuit according to the amplitude of an input signal in a communication system or a sound system. Background technique [0002] In a communication system or an audio system, an automatic gain control circuit that controls the gain of a variable gain amplifier circuit based on the amplitude of an input signal generally uses an integrating circuit using a capacitor. However, it is difficult to incorporate such an integrating circuit into a semiconductor integrated circuit because the capacitance value of the required capacitor is considerably large. [0003] As an AGC circuit that can be easily built into a semiconductor integrated circuit without using a capacitor, there is, for example, a circuit disclosed by the applicant of the present application (for example, refer to Patent Document 1). Conventional AGC circuits such as Figu...

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Problems solved by technology

Therefore, there is a problem of generating a strong sense of discomfort in hearing

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