A modified background calibration technique for multi-bit delta-sigma modulators

A digital background calibration technique for capacitors mismatch in multi-bit delta-sigma modulator is proposed in this paper. The approach is correlation-based, in which a single-bit pseudo-random noise (PN) is used to identify the error module, minimizing the analog circuit overhead. This algorithm works by estimating every DAC capacitor in turn with the PN signal injection and compensates for capacitor mismatch in digital domain. It is simple and requires minor circuit modification in analog domain. The tradeoff involved is the dynamic range degradation due to PN injection. Behavior level simulations demonstrate effective compensation for capacitors mismatch in a second-order modulator.