Heterojunction Bipolar Transistor Technology

Prior to the start of this program, the demonstrations of high-speed ECL-type circuits GaAlAsGaAs HBT technology had been limited to a few very small circuits such as ring oscillators, and frequency dividers. The high operating frequency of those circuits, the prospects of relatively straightforward scale-up to higher integration levels, and the projections of much higher possible speeds according to simulations indicated that the ECL approach with HBTs was worthwhile exploring further. A key objective in the formulation of the present program was to identify any major stumbling blocks that might prevent the technology from being later inserted into systems, including major yield or uniformity problems, reliability or radiation hardness issues, excessive temperature sensitivity, etc. Another objective was to investigate whether HBT circuits could lead to major improvements in the speed powernoise performance of interchip communication circuits output drivers and receivers with respect to GaAs MESFET circuits, by making use of the high drive capability of bipolars particularly in conjunction with complementary output circuits to eliminate the common-ground inductance noise. A final objective was to demonstrate applications-oriented HBT circuits with state-of-the-art performance. Accordingly, there were three tasks within the program. rh