THS4271-EP Datasheet, PDF (31/44 Pages) Texas Instruments – LOW NOISE, HIGH SLEW RATE, UNITY GAIN STABLE VOLTAGE FEEDBACK AMPLIFIER

THS4271-EP
www.ti.com
DESIGN TOOLS
Performance vs Package Options
The THS4271 is offered in different package options.
However, performance may be limited due to
package parasitics and lead inductance in some
packages. In order to achieve maximum performance
of the THS4271, Texas Instruments recommends
using the leadless MSOP (DRB) or MSOP (DGN)
packages, in addition to proper high-speed PCB
layout. Figure 93 shows the unity gain frequency
response of the THS4271 using the leadless MSOP,
MSOP, and SOIC package for comparison. Using the
THS4271 in a unity gain with the SOIC package may
result in the device becoming unstable. In higher gain
configurations, this effect is mitigated by the reduced
bandwidth. As such, the SOIC is suitable for
application with gains equal to or higher than +2 V/V
or (–1 V/V).
20
SOIC, R_f = 0 Ω
18
_ ^Rf
16
+
14
150 Ω
SOIC,
49.9 Ω
12
R_f = 100 Ω
10
8
SOIC, R_f = 200 Ω
6 Leadless MSOP, &
4
MSOP R_f = 0 Ω
2
0
−2
V_IN = 100 mV_PP
V_S =±5 V
−4
10 M
100 M
1G
f − Frequency − Hz
Figure 93. Effects of Unity Gain Frequency
Response for DIfferential Packages
Evaluation Fixtures, Spice Models, and
Applications Support
Texas Instruments is committed to providing its
customers with the highest quality of applications
support. To support this goal, evaluation boards have
been developed for the THS4271 operational
amplifier. Three evaluation boards are available: one
THS4271, both are configurable for different gains,
and a third for a gain of +1. These boards are easy to
use, allowing for straightforward evaluation of the
device. These evaluation boards can be ordered
through the Texas Instruments web site, www.ti.com,
or through your local Texas Instruments sales
representative. Schematics for the evaluation boards
are shown below.
SGLS270C – DECEMBER 2004 – REVISED APRIL 2010
The THS4271 EVM board shown in Figure 97
through Figure 100 is designed to accommodate
different gain configurations. Its default component
values are set to give a gain of 2. The EVM can be
configured in a gain of +1; however, it is strongly not
recommended. Evaluating the THS4271 in a gain of 1
using this EVM may cause the part to become
unstable. The stability of the device can be controlled
by adding a large resistor in the feedback path, the
performance is sacrificed. Figure 94 shows the
small-signal frequency response of the THS4271 with
different feedback resistors in the feedback path.
Figure 95 is the small frequency response of the
THS4271 using the gain of 1 EVM.
17
15
_ ^Rf
R_f = 50 Ω
13
+
150 Ω
11
49.9 Ω
R_f = 0 Ω
9
R_f = 100 Ω
7
5
R_f = 150 Ω
3
1
−1
−3 ^VIN ^{= 100 mV}PP
−5 ^{VS = ±5 V}
10M
100M
1G
f − Frequency − Hz
Figure 94. Frequency Response vs Feedback
Resistor Using the EDGE #6439527 EVM
4
3
_
+
2
150 Ω
49.9 Ω
1
0
−1
−2 ^{Gain = 1}
R_L = 150 Ω
−3
V_O = 100 mV_PP
V_S = ±5 V
−4
100 k 1 M
10 M 100 M 1 G
f − Frequency − Hz
10 G
Figure 95. Frequency Response
Using the EDGE #6443547 EVM
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Product Folder Link(s): THS4271-EP
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