ADC08D1020DEV/NOPB National Semiconductor, ADC08D1020DEV/NOPB Datasheet - Page 16

• Manufacturer Part Number: ADC08D1020DEV/NOPB
• Description: BOARD DEV FOR ADC08D1020
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of ADC08D1020DEV/NOPB

• Number Of Adc's: 2
• Number Of Bits: 8
• Sampling Rate (per Second): 1G
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: 870 mVpp
• Power (typ) @ Conditions: 1.6W @ 1GSPS
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: ADC08D1020
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADC08D1020DEV

10.3 FFT Options
FFT plots can be configured in many different
ways. Clicking the FFT Options button at the
top of the plot will display a dialog showing the
options for that particular plot. The software also
maintains default options for new FFT plots,
which are editable. The default FFT options may
be edited by choosing Default FFT Options from
the Settings menu. The options are:
Ø Total Harmonic Distortion (THD) is the
Ø Spurious-Free Dynamic Range (SFDR)
Ø Effective Number of Bits (ENOB, or
Ø Windowing: You may choose from one of
ratio, expressed in dBc, of the RMS total of
the first five harmonic levels at the output
to the level of the fundamental at the
output. THD is calculated as
where f
fundamental (output) frequency and f
through f
harmonic frequencies.
is the difference, expressed in dB, between
the RMS values of the input signal and the
peak spurious signal, where a spurious
signal is any signal present in the output
spectrum that is not present at the input.
Effective Bits) is another method of
specifying Signal-to-Noise and Distortion or
SINAD. ENOB is defined as
five different window functions.
window function is applied to the samples
before computing the FFT to compensate
for the fact that the sample set may not be
an integral number of wavelengths of the
input signal. In general, Flat-Top will give
the best results, but it may be easier to
compare data with other systems when the
windowing functions are the same.
and says that the converter is equivalent to
a perfect ADC of this (ENOB) number of
bits.
THD
ENOB
1
N
are the RMS power in the first N
20
is the RMS power of the
log
SINAD
f
. 6
2
2
02
L
. 1
f
1
76
2
f
N
2
The
2
10.4 Histogram Plots
Histogram plots are created by counting the
number of times each ADC output code appears
in a dataset. Histograms may be computed by
software, or by hardware. A software histogram
is computed from a dataset which is normally
128k samples or smaller. A hardware histogram
is collected directly by the hardware, and may
include millions of counts per code. The resulting
histogram will show discontinuities between
comparators, gain or offset errors, and other
common ADC system problems.
The Histogram plot also displays the number of
codes that were never counted (missing codes),
followed by the first ten such missing codes.
10.5 Information Viewer
The information viewer is not a plot, but it
displays a variety of useful information about the
dataset, such as the sampling rate, and any
warnings generated by the software. You may
also store comments about the dataset here, to
be saved in a WaveVision file.
Ø dB Scale: You may select to represent
Ø Harmonics: You may select the number of
Ø IMD
power on the FFT in dBc (decibels relative
to carrier), in which 0 dB is taken to be the
fundamental (carrier) power, or dBFS
(decibels relative to full-scale), in which 0
dB is taken to the be power contained in a
signal which uses the entire dynamic range
of the ADC.
harmonics recognized (and labeled) by the
software. You may also select the number
of FFT bins excluded around harmonics in,
for example, SNR calculations.
exclusion region around each harmonic will
be shown in a different color than the rest
of the data points.
software
Intermodulation
When two fundamental frequencies within
3 dBFS are present in the waveform, the
software
calculations. You may inhibit this behavior
by deselecting the Allow IMD calculation
checkbox.
enabled, you may also select whether the
software will include only 2
2
nd
and 3
Calculations:
rd
order terms.
will
is
When the IMD calculation is
capable
normally
Distortion
The
of
nd
perform
order or both
calculations.
WaveVision
performing
IMD
The
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