Patent ID: 6535030
Filing Date: 2003-03-18
Classification: H03F,H03K

Abstract:
An operational amplifier, comprising:a main current control branch comprising a first differential pair of transistors, each of the pair of first differential transistors are coupled in series with a diode connected transistor, the gates of the first differential pair are connectable to receive input voltages; an output branch comprising a pair of current mirror transistors each gate connected to a gate of one of the diode-connected transistors; a gain branch comprising a second differential pair of transistors, each of the pair of second differential transistors are connected to a drain of one of the current mirror transistors and gate connected to one of the input voltages; and a zeroing branch comprising, a tail current transistor having its drain coupled to ground, a third differential pair of transistors each connected between a gate of one of the diode connected transistors and the tail current transistor, each transistor of the third differential pair have a gate connected to a common mode reference voltage, and a fourth differential pair of transistors each connected between a drain of one of the current mirror transistors and the tail current transistor, and gate connected to one of a positive and a negative offset input.