OPERATIONAL AMPLIFIER CIRCUIT AND HEADPHONE AMPLIFIER

PROBLEM TO BE SOLVED: To minimize the occurrence of sound cracking or sound missing. SOLUTION: The operational amplifier circuit including folded cascode differential amplifier stages is provided with: load circuits comprising second P-type MOS transistors 51P, 52P connected in parallel with load circuits comprising first P-type MOS transistors 35P, 36P located between a power line 34 and drains of differential input N-type MOS transistors 31N, 32N; and load circuits comprising second N-type MOS transistors 51N, 52N connected in parallel with load circuits comprising first N-type MOS transistors 35N, 36N located between a ground line and drains of differential input P-type MOS transistors 31P, 32P. COPYRIGHT: (C)2006,JPO&NCIPI