High-performance sigma-delta ADC for ADSL applications in 0.35 /spl mu/m CMOS digital technology

We present a sigma-delta modulator designed for ADSL applications in a 0.35 /spl mu/m CMOS pure digital technology. It employs a 4th-order 3-stage cascade architecture including both single-bit and multi-bit quantizers with programmable resolution, which allows us to use an oversampling ratio of only 16 . Special emphasis is placed on technology issues, e.g. poor analog performance and substrate coupling. The measured performances are 13-bit dynamic range operating at 2 MS/s and 12-bit dynamic range operating at 4 MS/s. The modulator consumes 77 mW from a 3.3 V supply and occupies 1.32 mm/sup 2/.

[1]  A. Rodríguez-Vázquez,et al.  A 14-bit 4-MS / s Multi-bit Cascade Σ ∆ Modulator in CMOS 0 . 35-μ m Digital Technology , .

[2]  Ángel Benito Rodríguez Vázquez,et al.  A 13-bit, 2.2-MS/s, 55-mW multibit cascade ΣΔ modulator in CMOS 0.7-μm single-poly technology , 1999 .

[3]  I. Fujimori,et al.  A 90 dB SNR, 2.5 MHz output rate ADC using cascaded multibit /spl Delta//spl Sigma/ modulation at 8x oversampling ratio , 2000, 2000 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.00CH37056).

[4]  W. Sansen,et al.  A 3.3 V 15-bit delta-sigma ADC with a signal bandwidth of 1.1 MHz for ADSL-applications , 1999, Proceedings of the 24th European Solid-State Circuits Conference.

[5]  Belén Pérez-Verdú,et al.  A 13-bit, 2.2-MS/s, 55-mW multibit cascade /spl Sigma//spl Delta/ modulator in CMOS 0.7-/spl mu/m single-poly technology , 1999 .

[6]  Bruce A. Wooley,et al.  A 50-MHz multibit sigma-delta modulator for 12-b 2-MHz A/D conversion , 1991 .

[7]  Xavier Aragones,et al.  Analysis and Solutions for Switching Noise Coupling in Mixed-Signal ICs , 1999 .

[8]  L. Longo,et al.  A 90-dB SNR 2.5-MHz output-rate ADC using cascaded multibit delta-sigma modulation at 8/spl times/ oversampling ratio , 2000, IEEE Journal of Solid-State Circuits.

[9]  Ángel Rodríguez-Vázquez,et al.  High-order cascade multibit /spl Sigma//spl Delta/ modulators for xDSL applications , 2000, 2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353).

[10]  A. R. Feldman,et al.  A 13-bit, 1.4-MS/s sigma-delta modulator for RF baseband channel applications , 1998 .

[11]  W. Sansen,et al.  A 15-b resolution 2-MHz Nyquist rate /spl Delta//spl Sigma/ ADC in a 1-/spl mu/m CMOS technology , 1998 .