A TDC-Based Two-Step Quantizer With Swapper Technique for a Multibit Continuous-Time Delta-Sigma Modulator

作者：Lin Chen Chien^*; Weng Chan Hsiang; Wei Tzu An; Lin Yung Yu; Lin Tsung Hsien

来源：IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS, 2014, 61(2): 75-79.

DOI：10.1109/TCSII.2013.2291138

• Delta-sigma modulator
• inherent dynamic element matching (DEM)
• time-domain quantizer

A time-to-digital converter (TDC)-based two-step quantizer is proposed for a multibit continuous-time delta-sigma modulator (CTDSM). In the proposed time-domain quantizer, the barrel-shifting operation realizes the dynamic element matching (DEM) function inherently, eliminating an explicit DEM circuit and the associated circuit latency. The two-step quantization scheme further reduces the hardware and power consumption of a multibit TDC quantizer. A swapper technique, in addition to the inherent DEM, is incorporated to randomize the selection of the two banks of digital-to-analog converter cells, which ensure good linearity. A third-order CTDSM incorporating the proposed TDC-based two-step quantizer is fabricated in a 90-nm CMOS process. The modulator achieves a signal-to-noise-and-distortion ratio of 69.6 dB over a 1-MHz signal bandwidth. Operated from 1.2-V analog and 1-V digital supplies, the whole CTDSM consumes 1.79 mW and achieves a figure of merit of 361 fJ/conversion.

• 出版日期2014-2
• 单位中国科学院电工研究所