Datasheet
_
+
R
f
2.49 kΩ
49.9 Ω
0.1 µF 6.8 µF
−V
S
R
g
50-Ω Source
+
V
I
0.1 µF 6.8 µF
+
+V
S
V
O
2.49 kΩ
To Load
0
4
8
12
16
20
24
0.1 1 10 100
V
S
= 3 V
Gain = 10,
R
L
= 1 kΩ,
V
O
= 0.1 V
PP
R
F
= 100 kΩ
f − Frequency − MHz
R
F
= 1.65 kΩ
and 10 kΩ
Signal Gain − dB
0
4
8
12
16
20
24
0.1 1 10 100
V
S
= ±5 V
Gain = 10,
R
L
= 1 kΩ,
V
O
= 0.1 V
PP
R
F
= 100 kΩ
f − Frequency − MHz
R
F
= 2.5 kΩ
and 10 kΩ
Signal Gain − dB
THS4281
SLOS432A –APRIL 2004–REVISED NOVEMBER 2009
www.ti.com
APPLICATION INFORMATION
HIGH-SPEED OPERATIONAL AMPLIFIERS
The THS4281 is a unity gain stable, rail-to-rail input
and output, voltage-feedback operational amplifier
designed to operate from a single 2.7-V to 16.5-V
power supply.
Applications Section Contents
• Wideband, Noninverting Operation
• Wideband, Inverting Gain Operation
• Video Drive Circuits
• Single-Supply Operation
• Power-Supply Decoupling Techniques and
Recommendations
• Active Filtering with the THS4281
• Driving Capacitive Loads
Figure 68. Wideband, Noninverting Gain
• Board Layout
Configuration
• Thermal Analysis
• Additional Reference Material
• Mechanical Package Drawings
WIDEBAND, NONINVERTING OPERATION
Figure 68 shows the noninverting gain configuration
of 2 V/V used to demonstrate the typical performance
curves.
Voltage feedback amplifiers can use a wide range of
resistors values to set their gain with minimal impact
on frequency response. Larger-valued resistors
decrease loading of the feedback network on the
output of the amplifier, but may cause peaking and
instability. For a gain of +2, feedback resistor values
between 1 kΩ and 4 kΩ are recommended for most
applications. However, as the gain increases, the use
Figure 69. Signal Gain vs
of even higher feedback resistors can be used to
Frequency, V
S
= 3 V
conserve power. This is due to the inherent nature of
amplifiers becoming more stable as the gain
increases, at the expense of bandwidth. Figure 69
and Figure 70 show the THS4281 using feedback
resistors of 10 kΩ and 100 kΩ. Be cautioned that
using such high values with high-speed amplifiers is
not typically recommended, but under certain
conditions, such as high gain and good high-speed
printed circuit board (PCB) layout practices, such
resistances can be used.
Figure 70. Signal Gain vs
Frequency, V
S
= ±5 V
18 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated
Product Folder Link(s): THS4281