Patent ID: 6118340
Filing Date: 2000-09-12
Classification: H03F

Abstract:
A low noise differential amplifier, comprising:(a) a differential stage includingi. first and second load devices coupled between a first reference voltage and first and second conductors, respectively,ii. a resistor,iii. a first input transistor having a first electrode coupled to the first conductor and a second electrode coupled by a third conductor to a first terminal of the resistor, and a second input transistor having a first electrode coupled to the second conductor and a second electrode coupled by a fourth conductor to a second terminal of the resistor,iv. a first current source coupled to provide a first bias current, and a second current source coupled to provide a second bias current;(b) a first feedback amplifier including a third input transistor coupled between the third conductor and the first current source and having a gate electrode coupled to receive a first input signal, the first feedback amplifier producing a first signal on the control electrode of the first input transistor of the differential stage, the first bias current flowing through the first load device, the first input transistor, the third input transistor, and the first current source; and(c) a second feedback amplifier including a fourth input transistor coupled between the fourth conductor and the second current source and having a gate electrode coupled to receive a second input signal, the second feedback amplifier producing a second signal on the control electrode of the second input transistor, the second bias current flowing through the second load device, the second input transistor, the fourth input transistor, and the second current source.