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Wideband, Ultra-Low Noise, Voltage-Feedback

OPERATIONAL AMPLIFIER with Shutdown

APPLICATIONS

q HIGH DYNAMIC RANGE ADC PREAMPS

q LOW NOISE, WIDEBAND, TRANSIMPEDANCE

AMPLIFIERS

q WIDEBAND, HIGH GAIN AMPLIFIERS

q LOW NOISE DIFFERENTIAL RECEIVERS

q ULTRASOUND CHANNEL AMPLIFIERS

q IMPROVED UPGRADE FOR THE OPA687,

CLC425, AND LMH6624

FEATURES

q HIGH GAIN BANDWIDTH: 3.9GHz

q LOW INPUT VOLTAGE NOISE: 0.85nV/

√Hz

q VERY LOW DISTORTION: –105dBc (5MHz)

q HIGH SLEW RATE: 950V/

q HIGH DC ACCURACY: V

q LOW SUPPLY CURRENT: 18.1mA

q LOW SHUTDOWN POWER: 2mW

q STABLE FOR GAINS

Ultra-High Dynamic Range

Differential ADC Driver

DESCRIPTION

The OPA847 combines very high gain bandwidth and large

signal performance with an ultra-low input noise voltage

(0.85nV/

power saving is critical, the OPA847 also includes an op-

tional power shutdown pin that, when pulled low, disables the

amplifier and decreases the supply current to < 1% of the

powered-up value. This optional feature may be left discon-

nected to ensure normal amplifier operation when no power-

down is required.

The combination of very low input voltage and current noise,

along with a 3.9GHz gain bandwidth product, make the

OPA847 an ideal amplifier for wideband transimpedance

applications. As a voltage gain stage, the OPA847 is opti-

mized for a flat frequency response at a gain of +20V/V and

is stable down to gains as low as +12V/V. New external

compensation techniques allow the OPA847 to be used at

any inverting gain with excellent frequency response control.

Using this technique in a differential Analog-to-Digital Con-

verter (ADC) interface application, shown below, can deliver

one of the highest dynamic-range interfaces available.

OPA847

SBOS251E – JULY 2002 – REVISED DECEMBER 2008

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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Copyright © 2002-2008, Texas Instruments Incorporated

+5V

–5V

OPA847

+5V

+5V

–5V

850

Ω

39pF

OPA847

1.7pF

100pF

INP

INN

0.1

µF

1.7pF

850

Ω

39pF

100

Ω

20

Ω

2k

Ω

2k

Ω

20

Ω

0.001

µF

0.001

µF

1:2

50

Ω Source

< 5.1dB

Noise

Figure

ADS5500

14-Bit

125MSPS

100

Ω

100pF

V

CM

24.6dB Gain

Frequency (MHz)

DIFFERENTIAL OPA847 DRIVER DISTORTION

10

–70

–75

–80

–85

–90

–95

–100

–105

–110

20

30

40

50

2V

2nd-Harmonic

3rd-Harmonic

OPA8

47

OPA847 RELATED PRODUCTS

INPUT NOISE

GAIN BANDWIDTH

SINGLES

VOLTAGE (nV/

PRODUCT (MHz)

OPA842

2.6

200

OPA843

2.0

800

OPA846

1.2

1750

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

All trademarks are the property of their respective owners.