48-GHz digital ICs and 85-GHz baseband amplifiers using transferred-substrate HBT's

Using substrate transfer processes, we have fabricated heterojunction bipolar transistors with submicrometer emitter-base and collector-base junctions, minimizing RC parasitics and increasing f/sub max/ to 500 GHz. The process also provides a microstrip wiring environment on a low-/spl epsiv//sub r/ dielectric substrate. First design iterations of emitter-coupled-logic master-slave flip-flops exhibit 48 GHz maximum clock frequency when connected as static frequency dividers. Baseband amplifiers have been demonstrated with bandwidths up to 85 GHz.