Reference Design for Extending the OPA857 Transimpedance Bandwidth
The OPA857 is a wideband: ultralow noise transimpedance amplifier (TIA) targeted at photodiode monitoring applications. The OPA857 has two selectable gain configurations of 5kΩ and 20kΩ while maintaining a nearly constant closed-loop bandwidth in excess of 100MHz . In this reference design: external resistors are added in parallel with the internal resistors to take advantage of the high-speed amplifier core to extend the transimpedance bandwidth of the amplifier.
Extending the bandwidth of the OPA857 from 100MHz to greater than 250MHzAdjusting the gain of the OPA857 between 1-20kΩEvaluation module allows flexibility in testing the OPA857 in internal test mode or with an external photodiode