CANTILEVERED BASE InP DHBT FOR HIGH SPEED DIGITAL APPLICATIONS

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 (1-6). In this paper we report a novel InAIAs/InGaAs/InP double-HBT (DHBT) with a cantilevered base layer and undercut collector. We fabricated and demonstrated an 80 GHz 2:1 digital frequency divider, and a 5 GHz 8-bit phase/7-bit magnitude Direct Digital Synthesizer (DDS) chip with approximately 3000 transistors using this technology.