A novel effective bandpass semi-MASH sigma-delta modulator with double-sampling mismatch-free resonator

This paper presents a novel high-order bandpass semi-MASH sigma-delta modulator (4-2+2-...-2+2mb) with f/sub s//4 center frequency. The proposed topology employs a semi-MASH technique with a 4-2/sup L/mb topology to achieve an expandable and extendable high-order bandpass noise-shaping. To illustrate the architecture's behavior an 8xOSR 12-order 1.5-bit semi-MASH sigma-delta modulator is designed achieving 88 dB SNQR (signal-to-quantization-error ratio) at -1dB overloading point (90% of the modulator full-scale). A double-sampling mismatch-free single-opamp double-delay resonator is also proposed for the semi-MASH sub-stages to improve the overall design performance.