Robust PIN Photodiode With a Guard Ring Protection Structure

A guard ring (GR) structure is used to protect a planar InGaAs pin photodiode. The human body model (HBM) measurement results show that a photodiode with a GR, which is shorted to the cathode, is able to withstand an electrostatic discharge (ESD) threshold voltage of up to 200 V, whereas a similar photodiode without a GR structure can only withstand 50 V ESD threshold voltage. The capacitance and bandwidth measurement results show that the GR has negligible negative effects on the pin diode performance.