The operational amplifier phase compensating circuit and the operational amplifier null which uses

摘要

PROBLEM TO BE SOLVED: To reduce cost and to shorten a period required for a process by always giving bias voltage to MOS capacity where an n+ diffusion area is provided in an n- well and operating MOS capacity in an accumulation area with small voltage dependency. SOLUTION: A buffer amplifier constituted by using two P-type MOS transistors 4 and 6 operates to give a signal which level-shifts the output voltage of an operational amplifier in a positive direction to the upper face electrode of MOS capacity 10. Thus, MOS capacity 10 can operate in a state where positive voltage is normally biased and the voltage dependency of capacity is considerably small. Since the capacity operates in the accumulation area with small voltage dependency even if the voltage dependency of capacity exists, distortion does not occur in the signal transmitted to the gate terminal of the N-type MOS transistor 9 through the buffer amplifier.