OPA657
OPA
657
SBOS197B – DECEMBER 2001 – REVISED MAY 2004
1.6GHz, Low-Noise, FET-Input
OPERATIONAL AMPLIFIER
FEATURES
q
HIGH GAIN BANDWIDTH PRODUCT: 1.6GHz
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HIGH BANDWIDTH 275MHz (G = +10)
q
LOW INPUT OFFSET VOLTAGE:
±
0.25mV
q
LOW INPUT BIAS CURRENT: 2pA
q
LOW INPUT VOLTAGE NOISE: 4.8nV
/
Hz
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HIGH OUTPUT CURRENT: 70mA
q
FAST OVERDRIVE RECOVERY
DESCRIPTION
The OPA657 combines a high gain bandwidth, low distor-tion,
voltage-feedback op amp with a low voltage noise JFET-input
stage to offer a very high dynamic range amplifier for high
precision ADC (Analog-to-Digital Converter) driving or wideband
transimpedance applications. Photodiode applications will see
improved noise and bandwidth using this decompensated,
high gain bandwidth amplifier.
Very low level signals can be significantly amplified in a single
OPA657 gain stage with exceptional bandwidth and accuracy.
Having a high 1.6GHz gain bandwidth product will give >
10MHz signal bandwidths up to gains of 160V/V (44dB). The
very low input bias current and capacitance will support this
performance even for relatively high source impedances.
Broadband photodetector applications will benefit from the low
voltage noise JFET inputs for the OPA657. The JFET input
contributes virtually no current noise while for broadband
applications, a low voltage noise is also required. The low
4.8nV/
Hz
input voltage noise will provide exceptional input
sensitivity for higher bandwidth applications. The example
shown below will give a total equivalent input noise current of
1.8pA/
Hz
over a 10MHz bandwidth.
APPLICATIONS
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q
q
q
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WIDEBAND PHOTODIODE AMPLIFIER
WAFER SCANNING EQUIPMENT
ADC INPUT AMPLIFIER
TEST AND MEASUREMENT FRONT END
HIGH GAIN PRECISION AMPLIFIER
200kΩ TRANSIMPEDANCE BANDWIDTH
116
10MHz Bandwidth
RELATED OPERATIONAL AMPLIFIER PRODUCTS
SLEW VOLTAGE
V
S
BW RATE NOISE
(V) (MHz) (V/
µ
S) (nV/
√
HZ) AMPLIFIER DESCRIPTION
200
400
500
16
180
300
290
170
55
100
5.80
6
7
4.5
5.4
Unity-Gain
Unity-Gain
Unity-Gain
Unity-Gain
Unity-Gain
Stable
Stable
Stable
Stable
Stable
CMOS
FET-Input
FET-Input
FET-Input
FET-Input
Transimpedance Gain (dB)
106
DEVICE
96
86
OPA355 +5
OPA655
±5
OPA656
±5
OPA627
±15
THS4601
±15
76
0.1pF
200kΩ
66
100kHz
1MHz
Frequency
10MHz
50MHz
λ
(12pF)
OPA657
V
O
–V
b
Wideband Photodiode Transimpedance Amplifier
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.
All trademarks are the property of their respective owners.
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.
Copyright © 2001-2004, Texas Instruments Incorporated
www.ti.com
TI [ TEXAS INSTRUMENTS ]
