Low-Power CMOS ΣΔ modulators for speech coding

  • Eric van der Zwan

Abstract

A ΣΔ modulator with continuous-time loopfilter has some important advantages compared to its discrete-time counterpart. Bandwidth requirements to the active elements of the loopfilter are relaxed, so that power consumption is reduced. Furthermore, aliasing is reduced, eliminating the need for an anti-aliasing filter at the modulator input. A 4th order, 64 times oversampling ΣΔ modulator with microphone input was designed and shows 80 dB dynamic range over the 300–3400 Hz voice bandwidth. THD is −72dB for a 40mVRMS maximum input signal at 95 μA current consumption from a 2.2V supply voltage. The active die area of the modulator is 0.5 mm2 in a standard 0.5μm CMOS process.

Keywords

Attenuation Settling Active Element Candy Aliasing 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    F. de Jager, “Deltamodulation, a method of P.C.M. transmission using the I-unit code,” Philips Res. Rep, vol. 7, pp. 442–466, Nov. 1952.Google Scholar
  2. [2]
    H. Inose, Y. Yasuda, J. Murakami, “A telemetring system by code modulation - ΔΣ: modulation,” IRE Trans. Space Electronics and Telemetry, vol. 30, pp. 204–209, Sept 1962.CrossRefGoogle Scholar
  3. [3]
    J. C. Candy, “A use of double integration in sigma-delta modulation,” IEEE Trans. Commun., vol COM-33, no. 3, pp. 249–258, Mar. 1985.CrossRefGoogle Scholar
  4. [4]
    P.J.A. Naus, E.C. Dijkmans, “Multibit oversampled ΣΔ A/D converters as front end for CD players,” IEEE J. Solid-State Circuits, vol. 26, no. 7 pp. 905–909, July 1991.CrossRefGoogle Scholar
  5. [5]
    V. Comino, M.S.J. Steyaert, G.C. Temes, “A first-order currentsteering sigma-delta modulator,” IEEE J. Solid-State Circuits, vol. 26, no. 3, pp. 176–183, Mar. 1991.CrossRefGoogle Scholar
  6. [6]
    R.G. Lerch, M.H. Lankemeyer, H.L. Fiedler, W. Bradinal, P. Becker, “A monolithic sigma-delta A/D and D/A converter with filter for broad-band speech coding,” IEEE J. Solid-State Circuits, vol. 26, no. 12, pp. 1920–1927, Dec. 1991.CrossRefGoogle Scholar
  7. [7]
    Y. Matsuya, J. Yamada, “1V power supply, low-power consumption A/D conversion technique with swing-suppression noise shaping,” IEEE J. Solid-State Circuits, vol. 29, pp. 1524–1530, Dec. 1994.CrossRefGoogle Scholar
  8. [8]
    E.J. van der Zwan, E.C. Dijkmans, “A 0.2mW CMOS ΣΔ modulator for speech coding with 80 dB dynamic range,” ISSCC Dig. Tech. Papers, pp. 232–233, Feb. 1996.Google Scholar
  9. [9]
    S.H. Ardalan, J.J. Paulos, “An analysis of nonlinear behavior in delta-sigma modulators,” IEEE Trans. Circuits Syst, vol. CAS-34, no. 6, pp. 593–603, June 1987.CrossRefGoogle Scholar
  10. [10]
    R. Gregorian, G.C. Ternes, “Analog MOS Integrated Circuits for Signal Processing,” New York, Wiley, 1986.Google Scholar
  11. [11]
    F. Krummenacher, N. Joehl, “A 4-MHz CMOS continuous-time filter with on-chip automatic tuning,” IEEE J. Solid-State Circuits, vol. 23, no. 3, pp. 750–758, June 1988.CrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Eric van der Zwan
    • 1
  1. 1.Philips Research LaboratoriesEindhovenThe Netherlands

Personalised recommendations