Low-noise, wide offset range, programmable input offset amplifier front end and method

摘要

A programmable offset amplifier includes first (M1) and second (M2) input transistors having differentially connected sources and gates coupled to first (Vin+) and second (Vin-) input voltages. A tail current (Itail1) is shared between the first and second input transistors. First (M3) and second (M4) load devices are coupled between a reference voltage and drains of the first and second input transistors, respectively. An output stage (13) has a first input (+) coupled to the drain of the second input transistor and a second input (-) coupled to the drain of the first input transistor. Programmable voltage changes are produced on input elements of programmable input offset circuitry to cause changes in offset voltages associated with electrodes of the input transistors which are reflected back to the amplifier input to provide a large programmable input-referred offset voltage.