APPLICATIONS

q WIDEBAND PHOTODIODE AMPLIFIERS

q SAMPLE-AND-HOLD BUFFERS

q CCD OUTPUT BUFFERS

q ADC INPUT BUFFERS

q WIDEBAND PRECISION AMPLIFIERS

q TEST AND MEASUREMENT FRONT ENDS

DESCRIPTION

The OPA656 combines a very wideband, unity-gain stable,

voltage-feedback op amp with a FET-input stage to offer an

ultra high dynamic-range amplifier for ADC (Analog-to-Digital

Converter) buffering and transimpedance applications. Extremely

low DC errors give good precision in optical applications.

The high unity-gain stable bandwidth and JFET input allows

exceptional performance in high-speed, low-noise integrators.

The high input impedance and low bias current provided by

the FET input is supported by the ultra-low 7nV/

√Hz input

voltage noise to achieve a very low integrated noise in

wideband photodiode transimpedance applications.

Broad transimpedance bandwidths are achievable given the

OPA656’s high 230MHz gain bandwidth product. As shown

below, a –3dB bandwidth of 1MHz is provided even for a high

1M

Ω transimpedance gain from a 47pF source capacitance.

FEATURES

q 500MHz UNITY-GAIN BANDWIDTH

q LOW INPUT BIAS CURRENT: 2pA

q LOW OFFSET AND DRIFT:

q LOW DISTORTION: 74dB SFDR at 5MHz

q HIGH OUTPUT CURRENT: 70mA

q LOW INPUT VOLTAGE NOISE: 7nV/

Wideband, Unity-Gain Stable, FET-Input

OPERATIONAL AMPLIFIER

Frequency

1M

Ω TRANSIMPEDANCE BANDWIDTH

130

120

110

100

90

80

10kHz

100kHz

1MHz

5MHz

1MHz Bandwidth

OPA656

Wideband Photodiode Transimpedance Amplifier

(47pF)

λ

–V

b

499k

Ω

499k

Ω

V

O

1pF

OPA656

SBOS196G – DECEMBER 2001 – REVISED NOVEMBER 2008

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Copyright © 2001-2008, Texas Instruments Incorporated

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.

OPA656

SLEW VOLTAGE

BW

RATE

NOISE

DEVICE

(V) (MHz) (V/

OPA355

+5

200

300

5.8

Unity-Gain Stable CMOS

OPA655

±5

400

290

6

Unity-Gain Stable FET-Input

OPA657

±5 1600

700

4.8

Gain of +7 Stable FET-Input

OPA627

±15

16

55

4.5

Unity-Gain Stable FET-Input

THS4601

±15 180

100

5.4

Unity-Gain Stable FET-Input

RELATED OPERATIONAL AMPLIFIER PRODUCTS

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.

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