THS1408-EP_14 Datasheet, PDF (19/28 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
single-ended configuration
In this configuration, the input signal is level shifted by ΔREF/2.
10 kΩ + 10 kΩ
10 kΩ 10 kΩ
−
+
22 Ω
100 pF
100 pF
10 kΩ
IN+ ^REF+
THS1408
IN− _REF−
10 kΩ
Figure 18. Single-Ended With Level Shift
The following table shows the input voltages for negative full-scale output, zero output, and positive full-scale output:
ΔIN+ [V]
OUTPUT
−ΔREF
− full scale
0
0
ΔREF
+ full scale
Note that the resistors of the op-amp and the op-amp all introduce gain and offset errors. Those errors can be
trimmed by varying the values of the resistors.
Because of the added offset, the op-amp does not necessarily operate in the best region of its transfer curve (best
linearity around zero) and, therefore, may introduce unacceptable distortion. For ac signals, an alternative is
described in the following section.
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