Application of Heterojunction Bipolar Transistors to High Speed, Small-Scale Digital Integrated Circuits

The fabrication and performance of a number of small-scale (20-60 transistors) integrated circuits based on GaAs/(Ga,Al )As heterojunction bipolar transistors (HBTs) in an emitter-coupled logic approach are described. The circuits include ring oscillators, with propagation delay times down to 40 pS in current-mode logic gates; frequency dividers, operating with input frequencies up to 8.5 GHz; and a 4-bit pattern generator, operating with clock frequencies up to more than 2 GHz (data rates of 4-Gbit/s in nonreturn-to-zero format). Initial results of transistor uniformity and circuit yield are shown to be excellent.