ELECTRONIC CIRCUIT WITH UNIT FOR ATTENUATING AT LEAST ONE INPUT SIGNAL OF AMPLIFIER IN AUTOMATIC GAIN CONTROL LOOP

摘要

PROBLEM TO BE SOLVED: To provide an electronic circuit with a unit capable of smoothly attenuating one or more input signals and easy to implement while increasing the reliability of the electronic circuit.SOLUTION: The electronic circuit includes, in an automatic gain control loop, an input amplifier, an AGC unit connected to an output of the input amplifier to detect the amplitude of an output signal, and the unit for attenuating an input signal of the input amplifier on the basis of an adaptation signal from the AGC unit. The attenuation unit includes comparison means for comparing the adaptation signal with a reference signal and for supplying an attenuation current as a function of the difference between the adaptation signal and the reference signal to a diode-connected PMOS replica transistor, which is connected by a source to a common mode voltage dependent on the input signal of the amplifier. The replica transistor controls a PMOS shunt transistor defining a shunt resistance connected to the input of the amplifier.