A 7.2 mW 75.3 dB SNDR 10 MHz BW CT delta-sigma modulator using Gm-C-based noise-shaped quantizer and digital integrator

A 3^rd order continuous-time delta-sigma modulator using a Gm-C based noise-shaped integrating quantizer (NSIQ) with a digital back-end integrator is presented in this paper. By incorporating the back-end digital integrator, the conventional tradeoff between resolution and speed in time-based quantization is alleviated. Therefore by using only three clock edges and a low-power Gm-C, effective 4-bit quantization is achieved which also provides first order noise-shaping. The zero-crossing comparator is replaced by a preamplifier and three latches. The proposed modulator was fabricated in a 0.13μm CMOS process with an active area of 0.08mm². It operates at 640 MHz and achieves a peak SNDR of 75.3 dB and a peak SFDR of 94.1 dB in a 10 MHz bandwidth while consuming 7.2 mW from a 1.2V power supply.