Limiter circuit

Abstract

Abstract PURPOSE:To simplify the circuit constitution, by providing a variable resistor and a control circuit which changes the gain of a variable gain amplifier according to a control signal as an input resistor or a negative feedback resistor of said amplifier inserted between input and output terminals. CONSTITUTION:An input signal such as an audio signal supplied from an input terminal 21 is limited at a prescribed limitable level by a variable gain amplifier circuit 30 and fed to an output terminal 22. This circuit 30 consists of a variable resistive element 34 consisting of a CdS photoconductive cell, an operational amplifier 31 for inverting amplification, an input resistor 32, and a negative feedback resistor 33 for maximum gain control, and the resistance value of this element 34 is changed by a control signal from a control circuit 40 to change the gain of the circuit 30. A control signal is obtained from a compared output between an input signal from the input terminal 21 and an output signal from the output terminal 22 to feed the control signal to the element 34. Thus, the gain control can be made without using any conventional nonlinear circuit.

Inventors

• 👤 Kenzo Akagiri

Bibliographic Details