1 Features
1• High Gain Bandwidth Product: 1.6 GHz
• High Bandwidth 275 MHz (G = 10)
• Slew Rate 700 V/μs (G = 10, 1-V Step)
• Low-Input Offset Voltage: ±250 μV
• Low-Input Bias Current: 2 pA
• Low-Input Voltage Noise: 4.8 nV/√Hz
• High-Output Current: 70 mA
• Fast Overdrive Recovery

2 Applications
• Wideband Photodiode Amplifiers
• Wafer Scanning Equipment
• ADC Input Amplifiers
• Test and Measurement Front Ends
• High Gain Precision Amplifiers
• Optical Time Domain Reflectometry (OTDR)

3 Description
The OPA657 device combines a high gain-bandwidth,
low-distortion, voltage-feedback operational amplifier
with a low voltage noise JFET-input stage to offer a
very high dynamic range amplifier for high-precision
analog-to-digital converter (ADC) driving or wideband
transimpedance applications. Photodiode applications
achieve 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. The very low input bias
current and capacitance supports this performance
even for relatively high source impedance.
Broadband photodetector applications benefit from
the low voltage noise JFET inputs for the OPA657.
The JFET input contributes virtually no current noise,
which makes the device ideal for high-gain
photodiode applications.