A New Approach to Design Low Power Continues-Time Sigma-Delta Modulators
Authors: E. Farshidi
This paper presents the design of a low power second-order continuous-time sigma-delta modulator for low power applications. The loop filter of this modulator has been implemented based on the nonlinear transconductance-capacitor (Gm-C) by employing current-mode technique. The nonlinear transconductance uses floating gate MOS (FG-MOS) transistors that operate in weak inversion region. The proposed modulator features low power consumption (<80uW), low supply voltage (1V) and 62dB dynamic range. Simulation results by HSPICE confirm that it is very suitable for low power biomedical instrumentation designs.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1076196Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1223
 C. A. D. E. La Croz-Blas, A. J. Lopez-Martin and A. Carlosena, "1.2V 5uw class-AB CMOS log-domain integrator with multi decade tuning," IEEE. Trans. Circuits Syst. II, Analog Digit. Signal process. vol. 52, no.10, pp. 665-668, Oct. 2005.
 D. Payton and C .Enz, "A micro power class-AB CMOS Log-domain filter for DECT applications," IEEE J. solid-State Circuits, vol. 36, no. 7, pp. 1067-1075, Jul. 2001.
 E. Farshidi, "A Micropower Current-Mode Sigma-Delta Modulator for Biomedical Applications," Presented in the 17th IEEE Signal Process. and Communications Application Conference, SIU-09, pp. 856-859, Antalya, Turkey, April 2009.
 O. Shoaei and W. M. Snelgrove, "Design and implementation of a tunable 40MHz-10Mhz Gm-C band pass Delta-Sigma modulator," IEEE Transactions on Circuits and Systems-II, vol. 44, no. 7, pp. 521- 530, Jul. 1997.
 S. R. Norsworthy, R. Schreier, and G. C. Themes, Delta-Sigma Data Converters, Piscataway, NJ: IEEE Press, 1996.
 J. H. Nielsen, E. Bruun, "A low-power 10-bit continuous-time CMOS Sigma-Delta A/D converter," ISCAS Proceedings of the 2004 International Symposium on, Vol. 1 , May 2004 .
 J. A. Cherry, Theory, practice, and fundamental performance limits of high-speed data conversion using continuous-time delta-sigma modulator, Ph.D. thesis, Carleton University, Ottawa, Ontario, Canada, Nov. 1998.
 E. Farshidi, S. M. Sayedi, "A Second-order Low Power Current- Mode Continuous-Time Sigma-Delta Modulator," ASICON'07, Proceedings of the 7th IEEE International Conference on ASIC, Guilin, China, pp. 293-296, Oct. 2007.
 E. Farshidi, Analysis and Design of Current-Mode Companding Circuits, Examining their Nonlinear Behavior and Application in Data Converters, Ph.D. Thesis, Isfahan University of Technology, Iran, Mar. 2008.
 H. Aboushady and M. M. Louerat, "Low-power design of low-voltage current-mode integrators for continuous-time sigma-delta modulators," IEEE International Symposium on Circuits and Systems, ISCAS'01, Sydney, Australia, May 2001.
 C. C. Enz, F. Krummenacher, and E. A. Vittoz, "An analytical MOS transistor model valid in all regions of operation and dedicated to lowvoltage and low-current applications," Journal of Analog Integrated Circuits and Signal Processing, Kluwer Academic Publishers, vol. 8, no. 1, pp. 83-114, 1995.
 E. O. Rodriguez-villegas and H. Barnes, "Solution to trapped charge in FGMOS transistors," Electron. Lett. , vol. 39, pp. 1416-1417, Sep. 2003.
 E. Seevinck, "Companding current-mode integrator: A new circuit principle for continuous-time monolithic filters," Electron. Lett., vol. 26, no. 24, pp. 2046-2047, Nov. 1990.
 G. M. Sung D. A. Yao K. H. Chang S. R. Yao " A Second-Order Sigma-Delta Modulator with Switched-Current Memory Cell for Closed-Loop Motor Control System," 37th IEEE Publication International Symposium on Power Electronics Specialist Conference, PESC-06, Jeju, Korea, June 2006.
 J. Ramirez-Angulo, G. Gonzalez-Atamirano, S. C. Choi, "Modeling multiple-Input floating gate transistors for analog signal processing," in IEEE Int. Symp. Circuits Syst., ISCAS-97, vol. 4, pp. 2020-2023, 1997.
 D. Johns and K. Martin, "Analog Integrated Circuit Design", John Wiley & Sons, 1997.
 A. Agah, K. Vleugels, P. B. Griffin, M. Ronaghi, J. D. Plummer, and B. A.Wooley, "A high-resolution low-power oversampling ADC with extended- range for bio-sensor arrays," in 2007 IEEE VLSI Circuits Symp , pp. 244-245, Jun. 14-16, 2007.
 S. Y. Lee and C. J. Cheng, "A low-voltage and low-power adaptive switched-current sigma-delta ADC for bio-acquisition microsystems," IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 53, no. 12, pp. 2628- 2636, Dec. 2006.
 H.-Y. Lee, C.-M. Hsu, S.-C. Huang, Y.-W. Shih, and C.-H. Luo, "Designing low power of sigma delta modulator for biomedical application," Biomed. Eng. Applicat., Basis, Commun., no. 18, pp. 181-185, August 2005.