Patent ID: 7358814
Filing Date: 2008-04-15
Classification: H03F

Abstract:
1. A differential audio amplifier comprising: a differential input stage, for producing an output voltage in response to a differential audio input signal, wherein the differential input stage has a first input transistor and a second input transistor coupled to separate polarities of the differential audio input signal, wherein the first transistor has characteristics substantially matched to characteristics of the second transistor, and wherein a first bias voltage biases the first input transistor and a second bias voltage biases the second input transistor of the differential input stage; and a bias compensation module, operatively coupled to the differential input stage, including a current mirror circuit having a third transistor and a fourth transistor for controlling first bias voltage to be substantially equal to the second bias voltage and for increasing a voltage swing of the output voltage, the bias compensation module including a current equalizer module, operably coupled to the differential input stage for balancing a current offset produced by the bias compensation module wherein the current equalizer module includes a fifth transistor, and wherein the fifth transistor has characteristics substantially matched to characteristics of the fourth transistor.