This book opens with the basics of the design of opto-electronic interface circuits. The text continues with an in-depth analysis of the photodiode, transimpedance amplifier (TIA) and limiting amplifier (LA). To thoroughly describe light detection mechanisms in silicon, first a one-dimensional and second a two-dimensional model is developed. All material is experimentally verified with several CMOS implementations, with ultimately a fully integrated Gbit/s optical receiver front-end including photodiode, TIA and LA.