THS1401 Datasheet, PDF (18/22 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
single-ended configuration
In this configuration, the input signal is level shifted by ∆REF/2.
10 kΩ + 10 kΩ
10 kΩ 10 kΩ
–
+
22 Ω
100 pF
100 pF
10 kΩ
IN+ ^REF+
THS1401/3/8
IN– _REF–
10 kΩ
Figure 21. Single-Ended With Level Shift
The following table shows the input voltages for negative full-scale output, zero output, and positive full-scale
output:
∆IN+ [V]
OUTPUT
–∆REF
– full scale
0
0
∆REF
+ 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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