Wideband cascade delta-sigma modulator with digital correction for finite amplifier gain effects

The authors present an alternative approach to reducing the effects of finite amplifier open-loop gain in cascade delta-sigma modulators. The proposed gain compensation is carried out in the digital domain and thus requires no additional analogue circuitry. The method is illustrated by the example of a double third-order cascade circuit which, when properly compensated for finite gain effects, can yield 1-20 bit resolution with oversampling ratios as low as 16-24.