| 摘要 |
PURPOSE:To minimize an offset output at time of a small input signal and at the same time, enlarge a dynamic range by controlling the intensity of a supply current for drive to a differential amplifier according to the intensity of an output current from the differential amplifier. CONSTITUTION:An output current IL1 from a differential amplifier 30 formed with a pair of transistors contained and which generates a recitified output against an input signal is input to an output circuit 46 and at the same time, is supplied as a control input to a current control circuit 44. The current control circuit 44 is composed of a current output circuit 50 and a current addition circuit 52, positively feeding back an electric current proprotional to the value of an output current IL1 to a current supply terminal 38 on the differential amplifier 30 to be added to an electric current from a constant current source circuit 42. Consequently, it is possible to minimize an offset output at time of small input signal and at the same time, pick up an output corresponding to an input signal level and increase the maximum output. Thus a dynamic range can be enlarged. |
