Application of standard CMOS photodiodes in optical communication systems

In this work, applicability to the optical communication systems of photodiodes realized with standard CMOS fabrication processes, which can be integrated to microelectronic systems at low costs. A photodiode fabricated with UMC 180 nm standard CMOS process on a silicon substrate within a 1.05 mm × 1.00 mm area is experimented with as an optical receiver in a setup where LEDs of different visible wavelengths are used as sources. Performance of the CMOS photodiode was compared to that of a Thorlabs PDA10A-EC photodiode used as a reference. In the experiments, it was observed that the communication bandwidth of the reference photodiode is in the 0.87-1.68 MHz range and that the CMOS photodiode can achieve comparable bandwidths in the range of 0.70-1.37 MHz. A square wave of 200 kHz frequency can be carried via an optical communication system using the CMOS photodiode without suffering from significant distortions.