Photodiodes for Monolithic CMOS Circuit Applications

An optoelectrical power supply unit compatible with standard CMOS processes designed for microscale applications is presented. The system is based on an earlier version consisting of a photodiode that converts optical power to electrical power, and a dc/dc converter that increases the photodiode anode voltage to desirable levels. It has the ability to operate continuously or intermittently. The latter operation mode employs additional system elements and requires the modulation of the input laser beam. A prototype was fabricated in UMC 0.18- $\mu$m triple-well standard CMOS process along with a direct conversion self-mixing receiver block on a die of 1525 $\mu$ m $\times$ 1525  $\mu$m area. Performance measurements were done using a laser source of 650-nm wavelength at different power levels. For an input laser power of 80 mW, the source can provide an output current of 2.18 mA at a supply voltage of 1.2 V. The proposed system can be used to power integrated digital and low-power analog communication and medical microsystems.