THS4281DBVT datasheet(19/31 Pages) TI

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APPLICATION INFORMATION

HIGH-SPEED OPERATIONAL AMPLIFIERS

Applications Section Contents

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

WIDEBAND, NONINVERTING OPERATION

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

SLOS432 – APRIL 2004

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.

•

Wideband, Noninverting Operation

•

Wideband, Inverting Gain Operation

•

Video Drive Circuits

•

Single-Supply Operation

•

Power

Supply

Decoupling

Techniques

and

Recommendations

•

Active Filtering With the THS4281

Figure 68. Wideband, Noninverting Gain

•

Driving Capacitive Loads

Configuration

•

Board Layout

•

Thermal Analysis

•

Additional Reference Material

•

Mechanical Package Drawings

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 de-

crease loading of the feedback network on the output

of the amplifier, but may cause peaking and insta-

Figure 69. Signal Gain vs

bility. For a gain of +2, feedback resistor values

Frequency, VS = 3 V

between 1 k

Ω and 4 kΩ are recommended for most

applications. However, as the gain increases, the use

of even higher feedback resistors can be used to

conserve power. This is due to the inherent nature of

amplifiers becoming more stable as the gain in-

creases, at the expense of bandwidth. Figure 69 and

Figure 70 show the THS4281 using feedback re-

sistors 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-PCB layout

practices, such resistances can be used.

Figure 70. Signal Gain vs

Frequency, VS = ±5 V

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