Patent ID: 7302246
Filing Date: 2007-11-27
Classification: H03F

Abstract:
1. An apparatus, comprising: a programmable gain amplifier, said programmable gain amplifier having a differential output; and a calibration block to detect an offset at the differential and to adjust the detected offset by adjusting a differential gain of the differential output wherein: said programmable gain amplifier is an operational amplifier having a differential input and the differential output; and said calibration block includes: an offset-cancelled comparator coupled to the differential output to sample an output of the operational amplifier and to generate a digital signal indicating the output of the operational amplifier; a control logic block coupled to receive the digital signal from the comparator and to generate an offset value to set a difference of the differential output of the operational amplifier; and programmable trim resistors coupled to the differential input of the operational amplifier and coupled to the control logic block to receive a control signal to control an impedance of the programmable trim resistors to adjust the differential gain of the differential output.