OPA857EVM-978: Using the board at 250V for APD Bias

Hello Amar,

  You do not need to remove C4 and C5 capacitors to apply 250V DC bias. These capacitors are on supplies is used to suppress high-frequency noise in power supply signals. It also helps provides high transient currents to an IC if needed in high output current design.  You may be confusing these capacitors as AC coupling capacitors that block DC signals/information from an input/output. These capacitors are in series to input/output source to load, compared to decoupling capacitors that are placed in parallel to these DC supply sources. 

  Therefore, you may apply the 250V DC bias to VAPD (TP3).

Thank you,

Sima