1.4V 13μW 83dB DR CT-ΣΔ modulator with Dual-Slope quantizer and PWM DAC for biopotential signal acquisition

High-resolution Sigma-Delta (∑Δ) ADCs are increasingly used in portable medical applications for the measurement of biopotential signals. This paper presents the implementation and measurements of a novel ultra-low power low voltage multi-bit continuous-time sigma-delta (CT-∑Δ) modulator, whose quantizer and feedback DACs operate in the time domain. Instead of the conventional flash quantizer and mismatch corrected multi-bit feedback DACs, a Dual-Slope (DS) quantizer and a Pulse-Width Modulated (PWM) DACs have been adopted in this design. The modulator has been implemented in a standard 0.18μm CMOS technology and features 83dB dynamic-range (DR) for a signal bandwidth of 256Hz. When clocked at 917kHz it consumes 13.3μW from a 1.4V supply.

[1]  Jian Xu,et al.  A 9µW 88dB DR fully-clocked switched-opamp ΔΣ modulator with novel power and area efficient resonator , 2010, IEEE Custom Integrated Circuits Conference 2010.

[2]  Un-Ku Moon,et al.  A third-order DT ΔΣ modulator using noise-shaped bidirectional single-slope quantizer , 2011, 2011 IEEE International Solid-State Circuits Conference.

[3]  B. A. Wooley,et al.  A 1.8-V digital-audio sigma-delta modulator in 0.8-/spl mu/m CMOS , 1997 .

[4]  J. Johansson,et al.  A 16-bit 60/spl mu/W multi-bit /spl Sigma//spl Delta/ modulator for portable ECG applications , 2003, ESSCIRC 2004 - 29th European Solid-State Circuits Conference (IEEE Cat. No.03EX705).

[5]  B. Wooley,et al.  A 1.8-V digital-audio sigma-delta modulator in 0.8-μm CMOS , 1997, IEEE J. Solid State Circuits.

[6]  Jonny Johansson,et al.  A 16-bit 60 μ W Multi-Bit Σ ∆ Modulator for Portable ECG Applications , 2003 .

[7]  Xiaobo Wu,et al.  Power optimization of high performance ΔΣ modulators for portable measurement applications , 2010, 2010 IEEE Asian Solid-State Circuits Conference.

[8]  N. Krishnapura,et al.  A 90μW 15-bit ΔΣ ADC for digital audio , 2007, ESSCIRC 2007 - 33rd European Solid-State Circuits Conference.

[9]  Enrique Prefasi,et al.  Second-order multi-bit ΣΔ ADC using a Pulse-Width Modulated DAC and an integrating quantizer , 2009, 2009 16th IEEE International Conference on Electronics, Circuits and Systems - (ICECS 2009).

[10]  Refet Firat Yazicioglu,et al.  A 200 $\mu$ W Eight-Channel EEG Acquisition ASIC for Ambulatory EEG Systems , 2008, IEEE Journal of Solid-State Circuits.

[11]  Un-Ku Moon,et al.  A Third-Order DT $\Delta\Sigma$ Modulator Using Noise-Shaped Bi-Directional Single-Slope Quantizer , 2011, IEEE Journal of Solid-State Circuits.

[12]  Bill Yang Liu,et al.  0.9 V 58 μW 92 dB SNDR audio ΔΣ modulator with high efficiency low noise switched-opamp and novel DWA technique , 2011 .

[13]  M.A.T. Sanduleanu,et al.  A low noise, low residual offset, chopped amplifier for mixed level applications , 1998, 1998 IEEE International Conference on Electronics, Circuits and Systems. Surfing the Waves of Science and Technology (Cat. No.98EX196).

[14]  Bob Adams,et al.  ADC for Digital Audio , 2005 .