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Function Generator Specifications

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    Last Modified: March 31, 2021

    Refer to the following specifications and examples when generating signals using the LabVIEW PDM Acquisition Toolkit.

    Dynamic Range and Distortion Specifications

    SINAD, where test amplitude is 0.5 relative digital full scale
    Fourth order modulator >98 dB
    Fifth order modulator >124 dB
    Dynamic Range, where test amplitude is 0.0005 relative digital full scale
    Fourth order modulator >100 dB
    Fifth order modulator >126 dB
    * Measurement Conditions: PDM rate = 3.072 MHz; Modulator bandwidth = 20 kHz; Test signal = 1 kHz sine wave; Measurement bandwidth = Modulator bandwidth.

    Modulator Bandwidth

    SINAD as a Function of Modulator Bandwidth

    The following figure demonstrates the signal-to-noise and distortion ratio (SINAD) as a function of modulator bandwidth when the modulator order is 4 and 5.

    * Measurement Conditions: PDM rate = 3.072 MHz; Modulator bandwidth = 3 kHz to 46 kHz; Test frequency = 1 kHz; Test amplitude = 0.5 FS.

    Modulator Flatness as a Function of Modulator Bandwidth

    Fourth Order Modulator
    Modulator bandwidth ≤40 kHz Ripple DC to modulation bandwidth < ±0.004 dB
    Modulator bandwidth >40 kHz and ≤46 kHz Ripple DC to modulation bandwidth < ±0.01 dB
    Fifth Order Modulator
    Modulator bandwidth ≤40 kHz Ripple DC to modulation bandwidth < ±0.001 dB
    Modulator bandwidth >40 kHz and ≤46 kHz Ripple DC to modulation bandwidth < ±0.002 dB
    * Measurement Conditions: PDM rate = 3.072 MHz

    Spectral Characteristics

    The following figures demonstrate the averaged power spectrum when the modulator order is 4 and 5, respectively.

    * Measurement Conditions: PDM rate = 3.072 MHz; Modulator bandwidth = 20 kHz; Test frequency = 1 kHz; Test amplitude = 0.5 FS; Spectral resolution = 10 Hz; Window type = Hanning; Number of RMS averaging = 64.

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