Datasheet
_
+
THS4271
249 Ω
ADS807
12-Bit,
53 Msps
R
f
+5 V
249 Ω
49.9 Ω
V
I
R
g
-5 V
50 Ω
Source
R
ISO
0.1 µF
16.5 Ω
68 pf
0.1 µF
IN
IN
CM
1.82 kΩ
R
T
249 Ω
_
+
49.9 Ω
100 Ω
100 Ω
14-Bit,
400 MSps
DAC5675
3.3 V3.3 V
C
F
1 nF
249 Ω 49.9 Ω
1 nF
1 nF
C
F
249 Ω
249 Ω
_
+
THS4271
THS4271
RF
(out)
IF+
IF-
100 Ω
1 nF
249 Ω
_
+
THS4271
49.9 Ω
100 Ω
249 Ω
100 Ω
+5 V
-5 V
14-Bit,
400 MSps
DAC5675
RF
LO
124 Ω
249 Ω
249 Ω
3.3 V3.3 V
_
+
THS4271
49.9 Ω
50 Ω Source
249 Ω
6.8
pF
5 V
−5 V
33 pF
V
O
249 Ω
61.9 Ω
V
I
THS4271
THS4275
SLOS397F –JULY 2002–REVISED OCTOBER 2009
www.ti.com
For best performance, high-speed ADCs should be driven
differentially. See the THS4500 family of devices for more
information.
Figure 79. Driving an ADC With a
Single-Ended Input
Figure 81. Differential Mixer Drive Circuit
Using the DAC5675 and the THS4271
Using the THS4271 as a DAC Output Buffer
Two example circuits are presented here showing the
Active Filtering With the THS4271
THS4271 buffering the output of a digital-to-analog
converter. The first circuit performs a differential to
High-frequency active filtering with the THS4271 is
single-ended conversion with the THS4271
achievable due to the amplifier high slew-rate, wide
configured as a difference amplifier. The difference
bandwidth, and voltage-feedback architecture.
amplifier can double as the termination mechanism
Several options are available for high-pass, low-pass,
for the DAC outputs as well.
bandpass, and bandstop filters of varying orders. A
simple two-pole low pass filter is presented here as
an example, with two poles at 100 MHz.
Figure 80. Differential to Single-Ended
Conversion of a High-Speed DAC Output
Figure 82. A Two-Pole Active Filter With Two
Poles Between 90 MHz and 100 MHz
For cases where a differential signaling path is
desirable, a pair of THS4271 amplifiers can be used
as output buffers. The circuit depicts differential drive
into a mixer IF inputs, coupled with additional signal
gain and filtering.
24 Submit Documentation Feedback Copyright © 2002–2009, Texas Instruments Incorporated
Product Folder Link(s): THS4271 THS4275