The OPA657 is a high-gain-bandwidth (1.6-GHz) JFET amplifier designed for optical networking, photodiode, and data-acquisition applications. It combines a high-precision voltage feedback amplifier ...

The JFET amplifies the signal while dropping the impedance in order to drive a pair of NPN transistors which are used as a threshold amplifier. Once the voltage hits 3V, an LED is lit, indicating ...