| 摘要 |
PURPOSE:To change the current gain, by controlling a current source of a differential amplifier formed with the combination of two current mirror circuits. CONSTITUTION:The differential amplifier 15 is provided with the current source 16 whose current value IA is varied. An output current I3 of the current mirror circuit 11 is applied to a transistor (TR)Qi of the differential amplifier 15 and a part I6 of a current I2 from the current source 6 is applied to the collector. An output current I4 of the current mirror circuit 12 is applied to the other TRQj and a part I5 of a current I1 from the current source 5 is applied to the collector. Thus, in dividing a part of currents I1, I2 to the differential amplifier 15, collector currents I5, I6 being divided currents are controlled by controlling the current source 16. Thus, the current gain is varied. |
