Receiver capable of outputting a high quality signal without regard to

Abstract

A receiver includes a first amplifying circuit for amplifying an input signal to thereby output an amplified input signal. A reference voltage generating circuit has the same configuration as the first amplifying circuit and generates a reference signal having a reference voltage for the amplified input signal. A variable-gain amplifying circuit variably adjusts the gain of the level of a signal derived from the amplified input signal and reference signal. The variable-gain amplifying circuit includes a second amplifying circuit for amplifying the amplified input signal and reference signal for maintaining linearity to thereby output a pair of first differential signals and a pair of second differential signals having shifted levels. A first differential amplifier performs differential amplification based on the first differential signals. A second differential amplifier performs differential amplification based on the first differential signals with a higher gain than the first differential amplifier. A gain controller controls, based on the second differential signals, the gains of the first and second differential amplifiers with a control signal capable of varying gain allocation to said the two differential amplifiers. When the amplified input signal has an amplitude far greater than the reference signal, the gain controller causes a current to flow through only one of the two differential amplifiers. When the amplified input signal has an amplitude far smaller than the reference signal, the gain controller causes the two differential amplifiers to operate at the same time.