| 摘要 |
PURPOSE:To vary a differential gain with a control voltage by connecting the source electrode of a MOS transistor TR to one differential output terminal of a differential amplifying circuit and connecting the drain electrode to the other differential output terminal of the differential amplifying circuit and giving a control voltage to the gate electrode. CONSTITUTION:A P-channel MOS TR M26 is added. Its source electrode and drain electrode are connected output terminals delta21 and delta22 of the differential amplifying circuit, and an optional control voltage is given to a gate electrode G26. The differential gain approximates gm24/(dgs22+dgs24+2gds26) to have the effeet reducing the differential gain. Since dgs26 is varied from 60 to zero approximately in accordance with a voltage VGS applied between the gate and the source of the M26, the differential gain is varied from gm24/(gds22+gds24) to zero. |
