Impedance Modelling for High Frequency Unitraveling-Carrier Photodiodes

High-speed photodiodes stand out as potential candidates to enable next-generation communication systems working as mmWave/THz sources due to their intrinsic broadband behaviour. Impedance matching is an essential task in microwave engineering that enables an efficient delivery of the power generated by the source (i.e. photodiode) to the load (i.e. antenna). In this work, we analyse the impedance of a generic uni-travelling carrier photodiode and its dependency with frequency, bias voltage and other operational parameters. In addition, we present some calculations and use cases, highlighting the importance of properly matching this impedance in an actual system.