Patent ID: 7714651

Claim:
A circuit for rail-to-rail operation, comprising: an amplifier, including: an n-type differential pair that is arranged to receive a differential input signal, and to provide an n-type differential pair output signal based, in part, on the differential input signal; a p-type differential pair that is arranged to receive the differential input signal, and to provide a p-type differential pair output signal based, in part, on the differential input signal; an output stage; a first plurality of switches that are arranged to selectively couple the n-type differential pair output signal to the output stage; a second plurality of switches that are arranged to selectively couple the p-type differential pair output signal to the output stage; and switch control circuitry that is arranged to control the first plurality of switches and the second plurality of switches so that either the n-type differential pair output signal or the p-type differential pair output signal is coupled to the output stage depending on a value of an input common mode voltage that is associated with the differential input signal wherein the switch control circuitry includes a current comparator that is arranged to compare a current that is associated with the n-type differential pair output signal with a current that is associated with the p-type differential pair output signal, and wherein the switch control circuitry is arranged to control the first plurality of switches and the second plurality of switches such that either the n-type differential pair output signal or the p-type differential pair output signal is coupled to the output stage depending on a result of the current comparison.