Patent ID: 7733181
Filing Date: 2010-06-08
Classification: H03F

Abstract:
1. An amplifier circuit comprising: a differential amplifier circuit having a first circuit leg and a second circuit leg, wherein the first circuit leg has a first transistor in series with a first variable current source, and wherein the second circuit leg has a second transistor in series with a second variable current source; a feedback circuit coupled to the differential amplifier circuit for producing a differential feedback signal; and a bias circuit coupled to the feedback circuit for receiving the differential feedback signal, the bias circuit coupled to the first and second variable current sources for inversely varying the first variable current source with respect to the second variable current source in response to the differential feedback signal, wherein the first variable current source comprises a first cascode transistor in the first circuit leg that is coupled to a common current source, and wherein the second variable current source comprises a second cascode transistor in the second circuit leg that is coupled to the common current source.