Abstract: An open loop offset trim system for use with a differential amplifier includes a reference generator, an offset detector and a trim circuit. To reduce offset, the differential amplifier is placed in an open loop configuration, with both input terminals connected to receive a common reference signal from the reference generator. In response to an offset, the differential amplifier's output signal will essentially rail to either the supply voltage or the ground. In response to the logic level of the differential amplifier's output signal, the offset detector provides a control signal to the trim circuit to adjust the current conducted by one leg of the differential pair to reduce current mismatch in the legs of the differential pair. This process may be performed iteratively to control the trim circuit to incrementally adjust the current conducted by a leg of the differential pair during the trimming process.

Abstract: An open loop offset trim system for use with a differential amplifier includes a reference generator, an offset detector and a trim circuit. To reduce offset, the differential amplifier is placed in an open loop configuration, with both input terminals connected to receive a common reference signal from the reference generator. In response to an offset, the differential amplifier's output signal will essentially rail to either the supply voltage or the ground. In response to the logic level of the differential amplifier's output signal, the offset detector provides a control signal to the trim circuit to adjust the current conducted by one leg of the differential pair to reduce current mismatch in the legs of the differential pair. This process may be performed iteratively to control the trim circuit to incrementally adjust the current conducted by a leg of the differential pair during the trimming process.