Patent ID: 7453104

Claim:
An operational amplifier, comprising: a first differential amplifier circuit formed by a pair of first N-channel MOS transistors associated with a first tail current source, a pair of first load resistors and a first source follower circuit connected to said first load resistors, said first differential amplifier circuit being adapted to amplify first and second input signals and to output first and second output signals; a second differential amplifier circuit formed by a pair of second N-channel MOS transistors associated with a second tail current source, a pair of second load resistors and a second source follower circuit connected to said second load resistors, said second differential amplifier circuit being adapted to amplify said first and second input signals and to output third and fourth output signals; a pair of inverter circuits adapted to further amplify said third and fourth output signals, respectively; and a pair of output circuits adapted to output differential output signals and supplied with first and second output signals and output signals of said inverter circuits.