Analysis of non-uniform sampling effects in sigma-delta modulated signals

The effects of non-uniform sampling in the ΣΔ-modulated DAC are discussed in this paper. The non-uniform sampling of the ΣΔ-modulated signals causes in-band noise in the DAC, which will be compared with the harmonic distortions in switched capacitor circuit and the that due to the signal-dependent nonlinearity in the 1-bit DAC. We describe an error-driven edge selection algorithm that suppresses the in-band noise and its implementation. We also propose a model of the in-band noise caused by the non-uniform sampling, which predicts the noise reduction of the spectral shaping in the frequency domain quantitatively based upon the transition probability of the modulator output