Small Signal Analysis: High-Speed Photodetectors

This lecture covers the small signal analysis of high-speed photodetectors, focusing on the electronic components involved. The instructor begins by introducing the basic elements of the circuit, including the photodiode, protection elements, and coupling capacitors. The small signal model is described, highlighting the roles of load resistance, amplification, and bandpass filtering. The bandwidth is derived from the load resistance and capacitance values. The discussion then shifts to noise analysis, considering both the primary signal and dark current noise, which are amplified through the Avalanche process. The lecture emphasizes the importance of understanding the noise contributions from various sources, including the load resistor and amplifier. The final diagram summarizes the small signal analysis, integrating all noise sources and components to model the receiver system effectively. This comprehensive approach provides insights into optimizing high-speed photodetector performance in practical applications.