Patent ID: 7605645

Claim:
A transconductor for receiving a differential voltage signal and outputting a differential current signal, comprising: a first transconductor and a second transconductor for receiving the differential voltage signal and outputting a single-end current signal, wherein an inversion input terminal of one of the first and second transconductors is connected with a non-inversion input terminal of the other, and the transconductor outputs a current signal output from each of the first and second transconductors as the differential current signal, and wherein the first and second transconductors each comprise: a first voltage-to-current conversion circuit and a second voltage-to-current conversion circuit for receiving a positive side and a negative side of the differential voltage signal, respectively; and a current mirror circuit having an input side and an output side to which the first and second voltage-to-current conversion circuits are connected, respectively, wherein the single-end current signal is output from a connection point between the second voltage-to-current conversion circuit and the current mirror circuit, said transconductor further comprising: a first variable current source and a second variable current source connected any one of the input side and the output side of the current mirror circuit in each of the first and second transconductors; and a common-mode feedback circuit for controlling the first and second variable current sources based on a difference between an operating point voltage of a differential output of the transconductor and a reference voltage.