We report in this paper, the performance of AlGaN/GaN HFETs in the context of high power, low noise and high temperature operations, along with a comparison of their characteristics with other conventional technologies. Finally, a single stage modulator driver for long haul optical communications is presented as an example of application of the GaN-based devices high power handling capabilities.

This report describes AlGaAs/GaAs HBT ICs for 20-Gb/s optical transmission, the preamplifier and optical modulator driver circuits, and those ICs for 10-Gb/s clock extraction circuits, the rectifier and phase shifter circuits. These ICs were fabricated using our developed hetero guard-ring fully self-aligned HBT (HG-FST) fabrication process. The Pt-Ti-Pt-Au multimetal system was also used as a base ohmic metal to reduce base contact resistance, and a high fmax of 105 GHz was obtained. Good results in the HBT IC microwave performances were achieved from the on-wafer measurements. The preamplifiers exhibited the broad bandwidth of 20. 9 GHz. The optical modulator driver performed a sufficiently large output-voltage swing of 4-VP-P at a 20-Gb/s data rate. The rectifier and the phase shifter circuits achieved good operations at 10-Gb/s. These results suggest that these HBT ICs can be applied to 20-Gb/s optical transmission and 10-Gb/s clock extraction systems.