| 摘要 |
PURPOSE:To eliminate an offset of an output voltage due to a base current of an output emitter follower by providing a resistor to a base or an emitter of a transistor(TR) whose emitter connects to a base of a TR of a differential amplifier. CONSTITUTION:A resistor 26 is provided to a base of a TR 9 whose emitter connected to a base of a TR 4 of a differential amplifier. Let a current flowing to the TR 9 be IA, and when a current IAX10 being ten times the current IA is desired to be supplied to a TR 11 of an output emitter follower, and let hFE of the TRs 9,10 be 100 and a resistance of a resistor 16 be R, then the resistance of the resistor 26 provided to the base of the TR 9 is selected to be RX10. In this state, when switches 23,24 are turned for clamping, a base level of the TR 11 is VR+VBE+RX10XIA/hFE. When the clamping is released, the base level of the TR 11 reaches a level of VR+VBE, an output voltage at the emitter level of the TR 11 reaches VR and the level is equal to a level of a power supply 20. Thus, the offset is improved. |
