A 3.3fJ/conversion-step 250kS/s 10b SAR ADC using optimized vote allocation

This paper presents a 10b successive approximation register (SAR) analog-to-digital converter (ADC) that operates at 0.5V supply voltage and supports a flexible differential input dynamic range from 0.4V to 1V. The proposed ADC employs a majority vote comparison along with a non-binary architecture to alleviate the effect of comparator noise in scaled input voltage swings. To maximize performance subject to comparator power level constraints, the allocation of votes is optimized for each bit cycle. The prototype, fabricated in 65nm CMOS process, achieves ENOB ranging from 7.1b to 9.1b and FOM from 3.3 to 6.8fJ/conversion step while operating at 250kS/s.

[1]  Andrea Baschirotto,et al.  An 820μW 9b 40MS/s Noise-Tolerant Dynamic-SAR ADC in 90nm Digital CMOS , 2008, 2008 IEEE International Solid-State Circuits Conference - Digest of Technical Papers.

[2]  Arthur H. M. van Roermund,et al.  A 2.2/2.7fJ/conversion-step 10/12b 40kS/s SAR ADC with Data-Driven Noise Reduction , 2013, 2013 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[3]  A.P. Chandrakasan,et al.  An Ultra Low Energy 12-bit Rate-Resolution Scalable SAR ADC for Wireless Sensor Nodes , 2007, IEEE Journal of Solid-State Circuits.

[4]  Naveen Verma,et al.  Design considerations for ultra-low energy wireless microsensor nodes , 2005, IEEE Transactions on Computers.

[5]  Anantha Chandrakasan,et al.  A resolution-reconfigurable 5-to-10b 0.4-to-1V power scalable SAR ADC , 2011, 2011 IEEE International Solid-State Circuits Conference.

[6]  Tadahiro Kuroda,et al.  A 0.5 V 1.1 MS/sec 6.3 fJ/Conversion-Step SAR-ADC With Tri-Level Comparator in 40 nm CMOS , 2012, IEEE Journal of Solid-State Circuits.

[7]  Jae-Yoon Sim,et al.  A 21 fJ/Conversion-Step 100 kS/s 10-bit ADC With a Low-Noise Time-Domain Comparator for Low-Power Sensor Interface , 2011, IEEE Journal of Solid-State Circuits.

[8]  Andreas G. Andreou,et al.  A low-power 8-bit SAR ADC for a QCIF image sensor , 2011, 2011 IEEE International Symposium of Circuits and Systems (ISCAS).