The OPA657 combines a high gain bandwidth, low distortion, 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.