Investigation of a new technique for adaptive cancellation of noise in MOSFET Op. amps

Abstract EN

The paper presents a new technique for adaptive cancellation of noise in MOSFET IC operational amplifiers.

It employs two operational amplifiers, one is passive with its inverting and noninverting inputs short circuited.

This operational amplifier is only responsible to amplify its equivalent input noise and to give a proportional output voltage.

The second operational amplifier is active and is used to amplify the signal to be processed together with its equivalent input noise and gives, thus, a proportional output voltage.

The two operational amplifiers are coupled to each other through a common floating gate so that the noise of the passive amplifier is subtracted from the input of the second one and makes it, therefore, noise-free (~lnV/√H z or 0.1 µVrms within 2.5 kHz bandwidth) over a wide variety dynamic range of input voltage (~120 dB) and ambient temperature.

A feedback loop is added to improve the amplifier linearity (better than 2 %).

The standard 2 µm CMOS technology is used for the realization of the proposed noise-free operational amplifier.