Patent ID: 7864652

Claim:
A gain control circuit to determine gain by a current ratio of mutual conductance, comprising: a first gain control circuit in which positive and negative phase input signals are supplied, gain is changed based on a first control signal, and positive and negative phase output signals are outputted; a second gain control circuit in which the positive and negative phase input signals are supplied, gain is changed based on a second control signal, and the positive and negative phase output signals are outputted; and a load circuit in which the positive phase output signal of the first gain control circuit and the negative phase output signal of the second gain control circuit are synthesized and supplied to a first input terminal, and the negative phase output signal of the first gain control circuit and the positive phase output signal of the second gain control circuit are synthesized and supplied to a second input terminal, and the synthesized signals are lead out through mutual conductance set based on the first control signal and the second control signal, respectively.