Eugene G. Dierschke

A monolithic light-to-frequency converter with a scalable sensor array

A single-chip CMOS light to frequency converter provides light intensity measurements with an absolute accuracy of 5% and a selectable full scale sensitivity of either 1, 10 or 100 mW/ cm/sup 2/. The device incorporates a new switched-capacitor charge-metering current-to-frequency converter with an integral bandgap reference and exhibits a measured linearity error of 0.2% for a full scale frequency of 0.5 MHz and 1% for 1 MHz. A pin-programmable divider is included on the chip so that the output can be scaled for applications that require a lower frequency. An output enable is provided so that multiple units may share the same controller input line.<<ETX>>

Surface Emitting Sources For Optical Waveguides

The basic design principles of radiation emitting diodes are discussed. Theoretical and experimental values of radiant power, radiant intensity, and radiance of GaAs and GaAlAs infrared surface emitting sources are reviewed. A comparison of various device geometries shows that small-area, high-radiance, etched-well emitters are the optimum design for coupling to individual optical fibers but that high-radiant-intensity shaped emitters are the optimum design for coupling to larger diameter fiber bundles. Improved linearity can be achieved with GaAlAs planar emitters incorporating a buried-junction structure to minimize non-radiative surface recombination.