EVAL-ADAQ7980SDZ User Guide
UG-1060
Rev. 0 | Page 21 of 30
EVALUATION HARDWARE AND SOFTWARE OPERATION
The following section outlines how to use the
ADAQ798x
Evaluation Software
to capture, analyze and view conversion
results from the
ADAQ7980
.
CAPTURING CONVERSION RESULTS
The following describes how to collect conversion results from
the
EVAL-ADAQ7980SDZ
:
1.
Set the various controls in the
Configure
tab to the desired
values. See the Configure Tab section for a detailed
description of these controls.
2.
Once these controls have been set, conversions can be
initiated by pressing either the
Single Capture
or
Continuous Capture
buttons in the main window. See the
Overview of the Main Window section for more
information on these controls.
GENERATING A WAVEFORM ANALYSIS REPORT
Figure 23 illustrates the
Waveform
tab for a dc input signal when
using the on-board 5 V external reference.
The
Waveform Analysis
pane reports the amplitudes recorded
from the captured signal and the frequency of the signal tone.
GENERATING A HISTOGRAM OF THE ADC CODE
DISTRIBUTION
The
Histogram
tab can perform ac testing or, more commonly,
dc testing. This tab shows the ADC code distribution of the input
and computes the mean and standard deviation, which are
displayed as
DC Offset/Mean
and
Transition Noise (Pk-Pk)
,
respectively, in the
Histogram Analysis
pane.
Figure 24 shows the histogram of a dc signal applied to the ADC
input along with the resulting calculations.
AC Input
To perform a histogram test of ac input,
1.
Apply a sinusoidal signal with low distortion (better than
100 dB) to the evaluation board at the P1/P2 input SMA
connector pair.
2.
Click the
Histogram
tab from the main window.
3.
Click the
Single Capture
or
Continuous Capture
button.
Raw data is then captured and passed to the PC for statistical
computations, and various measured values are displayed in the
Histogram Analysis
pane.
DC Input
To perform a histogram test of dc input,
1.
If using an external source, apply a signal to the evaluation
board at the P1/P2 input SMA connector pair. It can be
required to filter the signal to ensure that the dc source is
noise compatible with the ADC.
2.
Click the
Histogram
tab from the main window.
3.
Click the
Single Capture
or
Continuous Capture
button.
Raw data is then captured and passed to the PC for statistical
computations, and various measured values are displayed in the
Histogram Analysis
pane.
GENERATING AN FFT OF AC CHARACTERISTICS
Figure 25 shows the
FFT
tab. This feature tests the traditional
ac characteristics of the ADC and displays an FFT plot of the
results.
To perform an ac FFT test,
1.
Apply a sinusoidal signal with low distortion (better than
100 dB) to the evaluation board at the P1/P2 input SMA
connector pair. To attain the requisite low distortion, which
is necessary to allow true evaluation of the
ADAQ7980
,
one option is to
a.
Filter the input signal from the ac source. A band-pass
filter can be used; its center frequency must match the
test frequency of interest.
b.
If using a low frequency band-pass filter when the full-
scale input range is more than a few volts peak-to-peak,
use the on-board amplifiers to amplify the signal, thus
preventing the filter from distorting the input signal.
2.
Click the
FFT
tab from the main window.
3.
Click the
Single Capture
button or
Continuous Capture
button.
As in the histogram test, raw data is then captured and passed
to the PC, which performs the FFT and displays the resulting
signal-to-noise ratio (SNR), signal-to-noise-and-distoriton ratio
(SINAD), total harmonic distortion (THD), and spurious-free
dynamic range (SFDR).
The
FFT Analysis
pane displays the results of the captured data.
