THS1401 Datasheet, PDF (19/22 Pages) Texas Instruments – 14-BIT, 1/3/8 MSPS DSP COMPATIBLE ANALOG-TO-DIGITAL CONVERTERS WITH INTERNAL REFERENCE AND PGA

THS1401, THS1403, THS1408
14-BIT, 1/3/8 MSPS DSP COMPATIBLE ANALOG-TO-DIGITAL CONVERTERS
WITH INTERNAL REFERENCE AND PGA
SLAS248 – DECEMBER 1999
APPLICATION INFORMATION
AC-coupled single-ended configuration
If the application does not require the signal bandwidth to include dc, the level shift shown in Figure 4 is not
necessary.
10 kΩ
10 kΩ
10 kΩ 10 kΩ
–
10 nF
+
22 Ω
100 pF
IN+ ^REF+
THS1401/3/8
100 pF
IN– _REF–
10 kΩ
10 kΩ
Figure 22. Single-Ended With Level Shift
Because the signal swing on the op-amp is centered around ground, it is more likely that the signal stays within
the linear region of the op-amp transfer function, thus increasing the overall ac performance.
IN [VPEAK]
–∆REF
0
∆REF
OUTPUT [PEAK]
– full scale
0
+ full scale
Compared to the transformer-coupled configuration, the swing on IN– is twice as big, which can decrease the
ac performance (SNR, SFD, and THD).
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