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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

Speech Code Versus Supply Voltage Input Transistor Clock Jitter Switch Capacitor Filter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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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

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