EVAL-AD7403FMCZ Datasheet, PDF (16/20 Pages) Analog Devices – Full featured evaluation board

UG-683
GENERATING A FAST FOURIER TRANSFORM OF
AC CHARACTERISTICS
Figure 19 shows the FFT tab. This feature tests the traditional
ac characteristics of the converter and displays a fast Fourier
transform (FFT) of the results.
To perform an ac FFT test,
1. Apply a bipolar sinusoidal signal with low distortion (better
than 115 dB) to the evaluation board at the VIN+ input.
To attain the requisite low distortion, which is necessary to
allow true evaluation of the part, one option is to filter the
input signal from the ac source. Choose an appropriate
band-pass filter based on the sinusoidal signal applied.
2. Click the FFT tab from the main window.
3. Click Single Capture or Continuous Capture.
EVAL-AD7403FMCZ User Guide
As in the histogram test, raw data is then captured and passed
to the PC, which performs the FFT and displays the resulting
SNR, THD, and SINAD.
Figure 19 displays the spectral analysis results of the captured data.
• The plot is the FFT image of the raw data.
• The FFT Analysis box displays the performance data:
SNR, THD, SINAD, dynamic range, and noise
performance along with the input signal characteristics
(see label 1 in Figure 19).
• Clicking Show Harmonic Content (see label 2 in Figure 19)
displays the frequency and amplitude of the fundamental
in addition to the second to fifth harmonics.
Figure 19. FFT Capture Tab
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