THS4281DBVT datasheet(18/37 Pages) NSC

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2.49 k

Ω

49.9

Ω

0.1

µF 6.8 µF

−VS

50-

Ω Source

0.1

µF 6.8 µF

+VS

2.49 k

Ω

To Load

0.1

100

VS = 3 V

Gain = 10,

RL = 1 kΩ,

VO = 0.1 VPP

RF = 100 kΩ

f − Frequency − MHz

RF = 1.65 kΩ

and 10 k

Ω

0.1

100

VS = ±5 V

Gain = 10,

RL = 1 kΩ,

VO = 0.1 VPP

RF = 100 kΩ

f − Frequency − MHz

RF = 2.5 kΩ

and 10 k

Ω

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

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 k

Ω 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, VS = 3 V

conserve power. This is due to the inherent nature of

amplifiers

becoming

stable

the

gain

increases, at the expense of bandwidth. Figure 69

and Figure 70 show the THS4281 using feedback

resistors of 10 k

Ω 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, VS = ±5 V

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