THS10064_09 Datasheet, PDF (35/42 Pages) Texas Instruments – 10-BIT, 4 ANALOG INPUT, 6 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTER

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THS10064
SLAS255B – DECEMBER 1999 – REVISED DECEMBER 2002
DC COUPLING
An operational amplifier can be configured to shift the signal level according to the analog input voltage range of the
THS10064. The analog input voltage range of the THS10064 goes from 1.5 V to 3.5 V. An op-amp specified for 5-V
single supply can be used as shown in Figure 44.
Figure 44 shows an application example where the analog input signal in the range from –1 V up to 1 V is shifted
by an op-amp to the analog input range of the THS10064 (1.5 V to 3.5 V). The op-amp is configured as an inverting
amplifier with a gain of –1. The required dc voltage of 1.25 V at the noninverting input is derived from the 2.5-V output
reference REFOUT of the THS10064 by using a resistor divider. Therefore, the op-amp output voltage is centered
at 2.5 V. The use of ratio matched, thin-film resistor networks minimizes gain and offset errors.
1V
0V
–1 V
R
1.25 V
R
5V
_
+
3.5 V
2.5 V
1.5 V
RS
THS10064
AINP
REFIN
REFOUT
R
R
Figure 44. Level-Shift for DC-Coupled Input
DIFFERENTIAL MODE OF OPERATION
For the differential mode of operation, a conversion from single-ended to differential is required. A conversion to
differential signals can be achieved by using an RF-transformer, which provides a center tap. Best performance is
achieved in differential mode.
Mini Circuits
T4–1
49.9 Ω
R
200 Ω ^C
R
C
THS10064
AINP
AINM
REFOUT
Figure 45. Transformer Coupled Input
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