Design of an Ultra-Low Power CT Sigma Delta A/D Modulator in 65 nm CMOS for Cardiac Pacemakers: From System Synthesis to Circuit Implementation
Abstract
A high performance, ultra-low power, fully differential 2nd-order continuous-time Sigma Delta analogue-to-digital modulator for cardiac pacemakers is presented in this paper. The entire design procedure is described in detail from the high-level system synthesis in both discrete and continuous-time domain, to the low-level circuit implementation of key functional blocks of the modulator. The power consumption of the designed modulator is rated at 182 nA from a 1.2V power supply, meeting the ultralow power requirement of the cardiac pacemaker applications. A 65 nm CMOS technology is employed to implement the Sigma Delta modulator. The modulator achieves a simulated SNR of 53.8 dB over a 400Hz signal bandwidth, with 32KHz sampling frequency and an oversampling ratio of 40. The active area of the modulator is 0.45 × 0.50mm2.
References
O. Aquilina, “A Brief History of Cardiac Pacing,” Images Paediatr Cardiol, vol. 8, no. 2, pp. 17.81, 2006.
M. A. Karami and D. J. Inman, “Powering Pacemakers from Heartbeat Vibrations using Linear and Nonlinear Energy Harvesters,” Applied Physics Letters, vol. 100, no. 4, p. 042901, 2012, doi 10.1063/1.3679102.
R. Schreier and G. C. Temes, Understanding Delta-Sigma Data Converters, 1st ed. Wiley-IEEE Press, November 2004, isbn 0471465852.
M. Ortmanns and F. Gerfers, Continuous-Time Sigma-Delta A/D Conversion: Fundamentals, Performance Limits and Robust Implementations, ser. Springer Series in Advanced Microelectronics. Springer, 2006, isbn 3540284060.
T. Song, Z. Cao, and S. Yan, “A 2.8-mW 2-MHz Continuous-Time Sigma Delta Modulator With a Hybrid Active-Passive Loop Filter,” IEEE Journal of Solid-State Circuits, vol. 43, no. 2, pp. 330.341, 2008.
J. Zhang, Y. Lian, L. Yao, and B. Shi, “A 0.6-V 82-dB 28.6-uW Continuous-Time Audio Delta-Sigma Modulator,” IEEE Journal of Solid-State Circuits, vol. 46, no. 10, pp. 2326.2335, 2011.
E. Lopez-Morillo, F. Munoz, A. Torralba, F. Marquez, I. Rebolle, and J. R. Garcia-Oya, “Compact Low-Power Implementation for Continuous-Time Sigma Delta Modulators,” Integration, the VLSI Journal, vol. 46, no. 4, pp. 441.448, 2012.
J. Garcia, S. Rodriguez, and A. Rusu, “A Low-Power CT Incremental 3rd Order Sigma Delta ADC for Biosensor Applications,” IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 60, no. 1, pp. 25.36, 2013.
B. E. Boser and B. A. Wooley, “The Design of Sigma-Delta Modulation Analog-to-Digital Converters,” IEEE Journal of Solid-State Circuits, vol. 23, no. 6, pp. 1298.1308, 1988.
D. A. Johns and K. Martin, Analog Integrated Circuit Design, 1st ed. Wiley, 1996, isbn 0471144487.
T. B. Cho and P. R. Gray, “A 10 b, 20 Msample/s, 35 mW Pipeline A/D Converter,” IEEE Journal of Solid-State Circuits, vol. 30, no. 3, pp. 166.172, 1995.
D. De Venuto, D. T. Castro, Y. Ponomarev, and E. Stikvoort, “0.8 uW 12-bit SAR ADC Sensors Interface for RFID Applications,” Microelectronics Journal, vol. 41, pp. 746.751, 2010.
J. H. Cheong, K. L. Chan, P. B. Khannur, K. T. Tiew, and M. Je, “A 400-nW 19.5-fJ/Conversion-Step 8-ENOB 80-kS/s SAR ADC in 0.18-um CMOS,” IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 58, no. 7, pp. 407.411, 2011.
D. Zhang, A. Bhide, and A. Alvandpour, “A 53-nW 9.1-ENOB 1-kS/s SAR ADC in 0.13-um CMOS for Medical Implant Devices,” IEEE Journal of Solid-State Circuits, vol. 47, no. 7, pp. 1585.1593, 2012.
I. Kianpour, M. Baghaei-Nejad, and L. Zheng, “78 nW Ultra-Low- Power 17 kS/s Two-Step-Successive Approximation Register Analogueto- Digital Converter for RFID and Sensing Applications,” IET Circuits, Devices & Systems, vol. 6, no. 6, pp. 397.405, 2012.
W. Hu, Y. Liu, T. Nguyen, D. Y. C. Lie, and B. P. Ginsburg, “An 8-Bit Single-Ended Ultra-Low-Power SAR ADC With a Novel DAC Switching Method and a Counter-Based Digital Control Circuitry,” IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 60, no. 7, pp. 1726.1739, 2013.
Y. Li, D. Zhao, and W. A. Serdijn, “A Sub-Microwatt Asynchronous Level-Crossing ADC for Biomedical Applications,” IEEE Transactions on Biomedical Circuits and Systems, vol. 7, no. 2, pp. 149.157, 2013.
C. Yuan and Y. Y. H. Lam, “A 281-nW 43.3 fJ/Conversion-Step 8-ENOB 25-kS/s Asynchronous SAR ADC in 65nm CMOS for Biomedical Applications,” in IEEE International Symposium on Circuits and Systems (ISCAS), Beijing, China, May 2013, pp. 622.625.
Downloads
Published
Issue
Section
License
1. License
The non-commercial use of the article will be governed by the Creative Commons Attribution license as currently displayed on https://creativecommons.org/licenses/by/4.0/.
2. Author’s Warranties
The author warrants that the article is original, written by stated author/s, has not been published before, contains no unlawful statements, does not infringe the rights of others, is subject to copyright that is vested exclusively in the author and free of any third party rights, and that any necessary written permissions to quote from other sources have been obtained by the author/s. The undersigned also warrants that the manuscript (or its essential substance) has not been published other than as an abstract or doctorate thesis and has not been submitted for consideration elsewhere, for print, electronic or digital publication.
3. User Rights
Under the Creative Commons Attribution license, the author(s) and users are free to share (copy, distribute and transmit the contribution) under the following conditions: 1. they must attribute the contribution in the manner specified by the author or licensor, 2. they may alter, transform, or build upon this work, 3. they may use this contribution for commercial purposes.
4. Rights of Authors
Authors retain the following rights:
- copyright, and other proprietary rights relating to the article, such as patent rights,
- the right to use the substance of the article in own future works, including lectures and books,
- the right to reproduce the article for own purposes, provided the copies are not offered for sale,
- the right to self-archive the article
- the right to supervision over the integrity of the content of the work and its fair use.
5. Co-Authorship
If the article was prepared jointly with other authors, the signatory of this form warrants that he/she has been authorized by all co-authors to sign this agreement on their behalf, and agrees to inform his/her co-authors of the terms of this agreement.
6. Termination
This agreement can be terminated by the author or the Journal Owner upon two months’ notice where the other party has materially breached this agreement and failed to remedy such breach within a month of being given the terminating party’s notice requesting such breach to be remedied. No breach or violation of this agreement will cause this agreement or any license granted in it to terminate automatically or affect the definition of the Journal Owner. The author and the Journal Owner may agree to terminate this agreement at any time. This agreement or any license granted in it cannot be terminated otherwise than in accordance with this section 6. This License shall remain in effect throughout the term of copyright in the Work and may not be revoked without the express written consent of both parties.
7. Royalties
This agreement entitles the author to no royalties or other fees. To such extent as legally permissible, the author waives his or her right to collect royalties relative to the article in respect of any use of the article by the Journal Owner or its sublicensee.
8. Miscellaneous
The Journal Owner will publish the article (or have it published) in the Journal if the article’s editorial process is successfully completed and the Journal Owner or its sublicensee has become obligated to have the article published. Where such obligation depends on the payment of a fee, it shall not be deemed to exist until such time as that fee is paid. The Journal Owner may conform the article to a style of punctuation, spelling, capitalization and usage that it deems appropriate. The Journal Owner will be allowed to sublicense the rights that are licensed to it under this agreement. This agreement will be governed by the laws of Poland.
By signing this License, Author(s) warrant(s) that they have the full power to enter into this agreement. This License shall remain in effect throughout the term of copyright in the Work and may not be revoked without the express written consent of both parties.
