“…Additionally, the current-irradiance relationship of the phototransistor is nonlinear, which makes it less than ideal to use in many applications. Like the photodiode, there are a number of possible configurations for the phototransistor in a standard CMOS process, such as the vertical p-np phototransistor and lateral p-n-p phototransistor [67][68][69][70][71]. A cross-section of a vertical p-n-p phototransistor is shown in Figure 17 and an example layout is provided in Figure 18.…”