Function Generator Specifications

Refer to the following specifications and examples when generating signals using the Digital Audio Acquisition and Generation Toolkit.

Introduced in Digital Audio Acquisition and Generation Toolkit 2021 Q2

Dynamic Range and Distortion Specifications

Measurement Conditions

PDM rate

3.072 MHz

Modulator bandwidth

20 kHz

Test signal

1 kHz sine wave

Measurement bandwidth

Modulator bandwidth

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

Modulator Bandwidth

SINAD as a Function of Modulator Bandwidth

Measurement Conditions

PDM rate

3.072 MHz

Modulator bandwidth

3 kHz to 46 kHz

Test frequency

1 kHz

Test amplitude

0.5 FS

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.

Figure 1. SINAD as Function of Modulator Bandwidth

SINAD as Function of Modulator Bandwidth

Modulator Flatness as a Function of Modulator Bandwidth

Measurement Conditions

PDM rate

3.072 MHz

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

Spectral Characteristics

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

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

Figure 2. Averaged Power Spectrum for Fourth Order Modulator

Averaged Power Spectrum for Fourth Order Modulator

Figure 3. Averaged Power Spectrum for Fifth Order Modulator

Averaged Power Spectrum for Fifth Order Modulator