Patent ID: 6492870
Filing Date: 2002-12-10
Classification: H03F

Abstract:
A differential input stage of an operational amplifier comprising:a first input transistor having a control node coupled to a first input node; a second input transistor having a control node coupled to the first input node; a third input transistor having a control node coupled to a second input node; a fourth input transistor having a control node coupled to the second input node; a first slewing transistor having a control node coupled to the first input transistor; a second slewing transistor having a control node coupled to the second input transistor and coupled in series with the first slewing transistor; a third slewing transistor having a control node coupled to the third input transistor; a fourth slewing transistor having a control node coupled to the fourth input transistor; a resistor having a first end coupled to the first and second slewing transistors and a second end coupled to the third and fourth slewing transistors; a first feed back circuit having an output coupled to the control node of the first slewing transistor and an input coupled to the first input transistor; a second feed back circuit having an output coupled to the control node of the second slewing transistor and an input coupled to the second input transistor; a third feed back circuit having an output coupled to the control node of the third slewing transistor and an input coupled to the third input transistor; and a fourth feed back circuit having an output coupled to the control node of the fourth slewing transistor and an input coupled to the fourth input transistor.