THS3215 Datasheet, PDF (44/71 Pages) Texas Instruments – THS3215 650-MHz, Differential to Single-Ended DAC Output Amplifier

THS3215
SBOS780A – MARCH 2016 – REVISED APRIL 2016
www.ti.com
9.3.3.3 Switch Feedthrough to the OPS
The THS3215 uses two logic control pins that enable one of four combinations of states; therefore, various
feedthrough effects must be considered. Figure 57 and Figure 58 show the feedthrough of the switches with the
OPS disabled. With the OPS enabled, the signal feedthrough from the deselected input to the OPS output is
shown in Figure 87 and Figure 88 at different closed-loop OPS gains. The results are shown for a 100-mV_PP
signal at the deselected input, and are not normalized to the gain of the OPS. When the external input of the
OPS is selected, add a low-pass filter between the DAC and the D2S inputs to reduce the feedthrough of the
DAC high-frequency content .
-20
-30
-40
-50
-60
-70
-80
-90
-100
1M
OPS Gain = 2.5 V/V
OPS Gain =10 V/V
10M
100M
Frequency (Hz)
PATHSEL < 0.7 V,
100-mV_PP signal to VIN (pin 9)
1G
D506
Figure 87. Forward Feedthrough With OPS Enabled,
Internal Path Selected
-20
-30
-40
-50
-60
-70
-80
-90
-100
1M
OPS Gain = 2.5 V/V
OPS Gain =10 V/V
10M
100M
Frequency (Hz)
PATHSEL > 1.3 V,
1G
D507
100-mV_PP signal to VREF (pin 14) with D2S inputs grounded
Figure 88. Forward Feedthrough With OPS Enabled,
External Path Selected
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