Patent ID: 6614304
Filing Date: 2003-09-02
Classification: H03F,H03G

Abstract:
A variable gain circuit comprising:a first transistor and a second transistor each having a control electrode connected to a first circuit input terminal; a load connected between a first power supply and a first electrode of at least one of said first transistor and said second transistor; a third transistor and a fourth transistor having second electrodes connected to said first transistor and said second transistor, respectively, and each having a first electrode and a control electrode connected to each other; a first variable current source connected between a second power supply and the second electrodes of said first transistor and said third transistor and having a current value variable according to an external control signal; a second variable current source connected between the second power supply and the second electrodes of said second transistor and said fourth transistor and having a current value variable according to said control signal; a current source connected between the first power supply and a node of the first electrodes and the control electrodes of said third transistor and said fourth transistor; and an impedance component having one end connected to the first electrodes and the control electrodes of said third transistor and said fourth transistor.