Ac Testing - Fft Capture - Analog Devices EVAL-AD7276SDZ User Manual

UG-xxx-AD7276

AC TESTING - FFT CAPTURE

Figure 18 shows the FFT capture tab This tests the traditional
AC characteristics of the converter and displays a Fast Fourier
Transform (FFT) of the results. As in the histogram test, raw
data is captured and passed to the PC where the FFT is
performed displaying SNR, SINAD, THD and SFDR. To
perform an AC test, apply a sinusoidal signal to the evaluation
board at the SMB inputs J4/63. Low distortion, better than
115dB, is required to allow true evaluation of the part. One
possibility is to filter the input signal from the AC source. There
is no suggested band-pass filter but consideration should be
taken in the choice. Furthermore, if using a low frequency
Figure 18. FFT Capture Tab
band-pass filter when the full-scale input range is more than a
few Vpp, it is recommended to use the on board amplifiers to
amplify the signal, thus preventing the filter from distorting the
input signal.
Figure 18 displays the results of the captured data.
1. Shows the input signal information
2. Displays the fundamental frequency and amplitude in
addition to the 2
3. Displays the performance data. SNR, Dynamic Range,
THD, SINAD, Noise performance.
Rev. PrA | Page 18 of 28
Evaluation Board User
nd to 5 th harmonics.
Guide