Sigma-Delta Voltage to Frequency Converter With Phase Modulation Possibility

Voltage to frequency converter (VFC) is an oscillator whose frequency is linearly proportional to control voltage. There are two common VFC architectures: the current steering multivibrator and the charge-balance VFC. For higher linearity, the charge-balancing method is preferred. The charge balanced VFC may be made in asynchronous or synchronous (clocked) forms. The synchronous charge balanced VFC or "sigma delta" (S-D) VFC is used when output pulses are synchronized to a clock. The charge balance VFC is more complex, more demanding in its supply voltage and current requirements, and more accurate. It is capable of 16 to18 bit linearity. In this paper, the New SVFC (NSVFC) is described. This NSVFC works similarly as conventional SVFC but it has a pure tone on output (for constant input voltage). Therefore, it is possible to measure the period of NSVFC output (this does not work for SVFC).

Sigma-Delta Voltage to Frequency Converter With Phase Modulation Possibility

Voltage to frequency converter (VFC) is an oscillator whose frequency is linearly proportional to control voltage. There are two common VFC architectures: the current steering multivibrator and the charge-balance VFC. For higher linearity, the charge-balancing method is preferred. The charge balanced VFC may be made in asynchronous or synchronous (clocked) forms. The synchronous charge balanced VFC or "sigma delta" (S-D) VFC is used when output pulses are synchronized to a clock. The charge balance VFC is more complex, more demanding in its supply voltage and current requirements, and more accurate. It is capable of 16 to18 bit linearity. In this paper, the New SVFC (NSVFC) is described. This NSVFC works similarly as conventional SVFC but it has a pure tone on output (for constant input voltage). Therefore, it is possible to measure the period of NSVFC output (this does not work for SVFC).

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  • Sangil Park, Ph. D.: Principles of Sigma-Delta Modulation for Analog-to-Digital Converters, Motorola Appli- cation Notes APR8, 1999.
  • Single and Multichannel, Synchronous Voltage-to-Frequency Converters, AD7741, AD7742, Analog Devices
  • Analog Multiplexers/Switches, Maxim 1995 New Releases Data Book, Vol. IV.
  • Stork M.: Modified Σ−∆ Voltage to Frequency Converter. 4-th International Conference on Advanced A/D and D/A Conversion Techniques and Their Applications. IMEKO TC-4, Prague, June 2002, ISBN 80-01-02540-3, pp. 211 - 214.
  • Stork M.: New Fractional Phase-Locked Loop Frequency Synthesizer Using a Sigma-Delta Modulator. 14th International Conference on Digital Signal Processing, DSP 2002, Santorini - Greece, July 2002, ISBN 0-7803- 3, Volume 1, pp. 367 - 370.
  • Stork M.: New Σ− ∆ Voltage to Frequency Converter. The 9th IEEE International Conference on Electronic Circuits and Systems, Proceedings, Dubrovnik, Croatia, September 2002, ISBN 0-7803-7596-3, Vol. II, pp. 634.
  • Stork M.: Voltage to Frequency Converter. 12th IMEKO TC4 International Symposium, Electrical Measure- ments and Instrumentation, Zagreb, Croatia, September 2002, ISBN 953-96093-8-0, Proceedings Part 2, pp. 467.