THS1408-EP_14 Datasheet, PDF (20/28 Pages) Texas Instruments – 14-BIT, 3/8 MSPS DSP-COMPATIBLE ANALOG-TO-DIGITAL CONVERTER WITH INTERNAL REFERENCE AND PGA

THS1408-EP
14-BIT, 3/8 MSPS DSP-COMPATIBLE ANALOG-TO-DIGITAL CONVERTER
WITH INTERNAL REFERENCE AND PGA
SGLS129B − JULY 2002 − REVISED FEBRUARY 2010
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+
THS1408
100 pF
IN− _REF−
10 kΩ
10 kΩ
Figure 19. 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 [V_PEAK]
−ΔREF
0
ΔREF
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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