A bandpass mismatch noise-shaping technique for Σ-Δ Modulators

A simple bandpass mismatch noise-shaping technique for Σ-Δ modulators is presented. This technique uses the data-directed scrambler structure and achieves ∼20 dB improvement in signal-to-noise ratio (SNR) for an oversampling ratio (OSR) of 32. Compared to the technique of bandpass mismatch noise shaping of Lin and Schreier, here, the SNR is improved by ∼ 7dB resulting in a 1-bit improvement in resolution. The selection logic is half the size of the logic in Lin and Schreier and is fully compatible with the low-pass selection logic of Kwan et al.. This compatibility allows implementation of bandpass/low-pass modulator as a single product.