Patent ID: 7728668

Claim:
A variable-gain amplification circuit, wherein the sources of first and second MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are tied to a common connection point connected to a current source, an input signal is supplied to the gates of said first and second MOSFETs, the drains of said first and second MOSFETs are connected to the sources of third and fourth MOSFETs respectively whereas the drains of said third and fourth MOSFETs are connected to two output terminals respectively, a gain control voltage is supplied to the gates of both said third and fourth MOSFETs, and when control is executed in order to lower said gain control voltage supplied to said gates of both said third and fourth MOSFETs, other control is also executed in order to raise a bias voltage applied to said gates of both said first and second MOSFETs.