69 GHz frequency divider with a cantilevered base InP DHBT

High speed digital logic is essential in diverse applications such as optical communication, frequency synthesizers, and analog-digital conversion. Current research efforts indicate that technologies utilizing heterojunction bipolar transistors (HBT) are the preferred approach for systems operating at clock frequencies of 40 GHz and above. In this paper we report a novel InAlAs/InGaAs/InP double-HBT (DHBT) with a cantilevered base layer and undercut collector. We fabricated and demonstrated a 69 GHz 2:1 digital frequency divider using this technology, which is, to our knowledge, the fastest divider reported to date in any semiconductor technology.