Apple Inc.
Amplifier Offset Cancelation

Abstract:

An amplifier system includes a differential amplifier and a calibration circuit. In response to a calibration operation, the calibration circuit generates a calibration value based on a test output signal generated by the differential amplifier circuit using a test input signal. The calibration value may be used to adjust loading of internal nodes of the differential amplifier circuit to compensate for imbalance in the differential amplifier circuit resulting from variation in manufacturing. By compensating for the imbalance, the offset of the differential amplifier may be reduced, allowing resolution of smaller differential voltages, thereby improving the performance of circuits employing the differential amplifier circuit.