Patent ID: 7382183
Filing Date: 2008-06-03
Classification: H03F

Abstract:
1. An auto-zeroing differential amplifier, comprising: a main amplifier having differential inputs, differential outputs, and an auxiliary port having differential inputs; a first nulling amplifier configured for differential and common mode self correction, the first nulling amplifier having differential inputs and outputs; a second nulling amplifier configured for differential and common mode self correction, the second nulling amplifier having differential inputs and outputs; first nulling amplifier input zeroing switches coupled to the main amplifier differential inputs and the first nulling amplifier differential inputs, wherein the first nulling amplifier input zeroing switches are used during offset zeroing of the main amplifier by the first nulling amplifier; second nulling amplifier input zeroing switches coupled to the main amplifier differential inputs and the second nulling amplifier differential inputs, wherein the second nulling amplifier input zeroing switches are used during offset zeroing of the main amplifier by the second nulling amplifier; first nulling amplifier output switches coupled between the first nulling amplifier differential outputs and the main amplifier auxiliary port differential inputs, wherein the first nulling amplifier output switches couple the first nulling amplifier differential outputs to the main amplifier auxiliary port differential inputs during offset zeroing of the main amplifier by the first nulling amplifier; and second nulling amplifier output switches coupled between the second nulling amplifier differential outputs and the main amplifier auxiliary port differential inputs, wherein the second nulling amplifier output switches couple the second nulling amplifier differential outputs to the main amplifier auxiliary port differential inputs during offset zeroing of the main amplifier by the second nulling amplifier; wherein when one of the nulling amplifiers is offset zeroing the main amplifier, the other nulling amplifier is doing a common-mode self offset zeroing.