Ultrahigh-speed direct digital synthesizer using InP DHBT technology

Direct digital synthesizers (DDS) offer advantages such as precise beam shaping and forming over conventional RF approaches. This paper discusses novel design and process techniques that enable direct digital synthesis of S-band output frequencies using our current InP double-heterojunction bipolar transistor technology with a cantilevered base layer and undercut collector. The DDS chip operates at the world record clock rate of 9.2 GHz and capable of generating sinewaves up to 4.56 GHz. It also demonstrates state-of-the-art phase noise of -140 dBc at a frequency offset of 1 kHz and a clock frequency of 2.5 GHz. Further design and process improvements will be implemented in future generation circuits that will enable synthesis of Ku-band frequencies.