This paper describes the electrical and spectral characteristics of different layers to construct photosensitive elements in standard 1.2 mu m CMOS technology. The use of commercial CMOS processes guarantees good reproduceability of the integrated sensors and optimized cointegration with sensor signal conditioning circuits. Deep and shallow photosensitive PN diodes and a vertical PNP phototransistor are investigated. Electrical on-wafer measurements with optical stimulation are performed and parameter extraction algorithms are established to create SPICE models. These models are suitable for the development of opto-ASICs. The validity of the model is tested using a 0.3 mm2 photodiode together with a two-stage transimpedance amplifier with a transimpedance of 5 MOhm at a 3 dB bandwidth of 90 kHz. the whole circuit is packaged using an optically transparent window in a plastic package.