THS1206 Datasheet, PDF (31/41 Pages) Texas Instruments – 12-BIT 6 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS

THS1206
12-BIT 6 MSPS, SIMULTANEOUS SAMPLING
ANALOG-TO-DIGITAL CONVERTERS
SLAS217D – MAY 1999 – REVISED APRIL 2000
dc coupling
An operational amplifier can be configured to shift the signal level according to the analog input voltage range
of the THS1206. The analog input voltage range of the THS1206 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 19.
Figure 19 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 THS1206 (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 THS1206 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
THS1206
AINP
REFIN
REFOUT
R
R
Figure 19. 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
THS1206
AINP
AINM
REFOUT
Figure 20. Transformer Coupled Input
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