Patent ID: 6937099
Filing Date: 2005-08-30
Classification: H03F

Abstract:
1. An operational amplifier (op-amp) configurable in a non-inverting mode with a closed loop gain greater than one, and with correction in an output signal of the op-amp for a time varying voltage reference of the op-amp relative to a true voltage reference, the op-amp comprising: a primary output for providing the output signal gained up from an input signal, a primary differential input amplifier stage operable with a transconductance and having a non-inverting input defining a primary non-inverting input of the op-amp for receiving the input signal, an inverting input defining a primary inverting input of the op-amp for coupling to a feedback loop from the primary output, and an output for providing an intermediate current signal from which the output signal on the primary output is derived, and a secondary differential input amplifier stage operable with a transconductance, and responsive to the time varying voltage reference for providing a secondary current signal responsive to variation in the time varying voltage reference relative to the true voltage reference for summing with the intermediate current signal provided by the primary differential input amplifier stage, the transconductance of the secondary differential input amplifier stage being a function of the transconductance of the primary differential input amplifier stage, so that the output signal on the primary output derived from the sum of the intermediate and secondary currents includes correction for the time varying voltage reference.