A 250+dB open loop gain feedforward compensated high precision operational amplifier

A stand alone operational amplifier with open loop gain >250db at 200Hz has been designed. It uses non-traditional feedforward compensation technique with five integrators to achieve such a high gain. It operates between 2.7 and 6.7 supply voltage. This amplifier has low offset voltage (<4uV), low noise(6.5nV/sqrtHz), 1/f corner at 0.03Hz with power supply current of 1.8mA. It can drive a load of 2kohm and 100pf in parallel. This amplifier combines performance of high precision bipolar with offset stability of a chopper in a CMOS process. It is targeted towards the applications where the input signal is low frequency < 1kHz and the signal level is in mV range and a high THD is required.