S
P
THD = 10Log 10
P
D
(3)
SINAD 1.76
ENOB =
6.02
−
(4)
5.5
Time Domain
User Interface
www.ti.com
Effective Number of Bits (ENOB) – The ENOB is a measure of a converter’s performance as compared to
the theoretical limit based on quantization noise
Time Domain
Several of the statistics of the Time Domain test are repeated here, particularly the minimum and
maximum sample values in the FFT record length, as well as the mean and standard deviation of the
sample values
Signal
The frequency of the expected input signal is reported, as well as the power level of the signal in either
dBc or dBFS. The amplitude of the input frequency for typical data sheet measurements is commonly set
externally to be about 1 dB below Full Scale, or –1 dBFS.
Distortion
The power values for the second, third, fourth, and fifth harmonics of the input frequency and the
user-selectable marker are displayed in either dBFS or dBc.
Test setup
Input parameters relevant to the test are repeated, particularly FFT record length, sample rate, and the
end points of the bandwidth of integration for noise calculations. The lower end point for the bandwidth of
integration is normally not zero because the first few FFT bins are not included to remove any DC biasing
component of the signal.
Figure 11. User Interface Single FFT format
The Time Domain test is shown in
. The larger central pane displays the raw sampled data
whereas the calculated statistics are grouped into categories on the right of the screen. Settings and
inputs relevant to the test are entered in drop-down menus or text input boxes on the left portion of the
window.
20
TSW1200EVM: High-Speed LVDS Deserializer and Analysis System
SLAU212A – April 2007 – Revised August 2008
