LAUSR

Chopping is a technique to reduce offset and flicker noise in amplifiers by up-converting them to higher frequency, and subsequently filtering them out. A typical chopping implementation uses two complementary phases which have a finite non-overlap time in between them. When such a chopping phase is used in the first integrator of a continuous-time delta sigma modulator, the non-overlap time can significantly degrade two key parameters of the modulator’s performance—in-band noise and its inherent anti-aliasing. In this paper, we develop a model to include the effects of non-overlap duration on the modulator’s performance. Then this model is used to derive analytical expressions for in-band noise and anti-aliasing for a given non-overlap duration. The results obtained are verified using simulation.