Datasheet

V
S
R
S
R
G
R
F
R
F
+
R
T
+
R
ISO
C
L
R
G
Riso=10 25- W
V
S
-V
S
R
ISO
-
-
_
+
4
5
3
7
2
6
V
OCM
S
PwrPad
V
S
PD
1
8
R0805
R4
C4
C0805
R5
R0805
C3
C0805
R6
R7
R0805
R0805
C5
C6
C0805
C0805
C7
C0805
J2
J3
J2
J3
R2
R0805
R3
R0805
C1
C0805
C2
C0805
R1
R1206
J1
3
1
4
5
6
R11
R1206
R9
R0805
R8
R9
R0805
R0805
J2
J3
J4
T1
U1
THS450X
-V
THS4500
THS4501
SLOS350F –APRIL 2002–REVISED OCTOBER 2011 www.ti.com
THS4501 product folder on the Texas Instruments
web site, www.ti.com, or through your local Texas
Instruments sales representative. A schematic for the
evaluation board is shown in Figure 116 with the
default component values. Unpopulated footprints are
shown to provide insight into design flexibility.
Figure 115. Use of Isolation Resistors With a
Capacitive Load
POWER-SUPPLY DECOUPLING
TECHNIQUES AND RECOMMENDATIONS
Power-supply decoupling is a critical aspect of any
high-performance amplifier design process. Careful
decoupling provides higher quality ac performance
(most notably improved distortion performance). The
following guidelines ensure the highest level of
performance.
Figure 116. Simplified Schematic of the
Evaluation Board
1. Place decoupling capacitors as close to the
power-supply inputs as possible, with the goal of
minimizing the inductance of the path from
Computer simulation of circuit performance using
ground to the power supply.
SPICE is often useful when analyzing the
performance of analog circuits and systems. This
2. Placement priority should be as follows: smaller
practice is particularly true for video and RF amplifier
capacitors should be closer to the device.
circuits where parasitic capacitance and inductance
3. Use of solid power and ground planes is
can have a major effect on circuit performance. A
recommended to reduce the inductance along
SPICE model for the THS4500 family of devices is
power-supply return current paths.
available through either the Texas Instruments web
4. Recommended values for power-supply
site (www.ti.com) or as one model on a disk from the
decoupling include 10-μF and 0.1-μF capacitors
Texas Instruments Product Information Center
for each supply. A 1000-pF capacitor can be
(1-800-548-6132). The PIC is also available for
used across the supplies as well for extremely
design assistance and detailed product information at
high frequency return currents, but often is not
this number. These models do a good job of
required.
predicting small-signal ac and transient performance
under a wide variety of operating conditions. They are
EVALUATION FIXTURES, SPICE MODELS,
not intended to model the distortion characteristics of
AND APPLICATIONS SUPPORT
the amplifier, nor do they attempt to distinguish
between the package types in their small-signal ac
Texas Instruments is committed to providing its
performance. Detailed information about what is and
customers with the highest quality of applications
is not modeled is contained in the model file itself.
support. To support this goal, an evaluation board
has been developed for the THS4500 family of fully
differential amplifiers. The evaluation board can be
obtained by ordering through the THS4500 or
34 Submit Documentation Feedback Copyright © 2002–2011, Texas Instruments Incorporated
Product Folder Link(s): THS4500 THS4501