Improved Chopper Stabilized Amplifier for Offset and 1/f Noise Cancellation

The limits of the conventional chopper stabilization technique for cancelling the 1/f noise are studied theoretically and with simulations. The expected replicas of the 1/f noise at the chopping frequency and its multiples are attenuated by a modified chopping control. Simulation done using records of real 1/f noise outputs show that the spectrum of the signal does not change but 1/f replicas are reduced by more than 40 dB. The required circuit for the generation of the chopping signal is also described. The resulting overhead with respect to conventional solutions is negligible and fully acceptable.