Compared to SiGe, InP HBTs offer superior electron transport properties but inferior scaling and parasitic reduction. Figures of merit for mixed-signal ICs are developed and HBT scaling laws introduced. Device and circuit results are summarized, including a simultaneous 450 GHz f,tau and 490 GHz f,max DHBT, 172 GHz amplifiers with 8.3-dBm output power and 4.5-dB associated power gain, and 150 GHz static frequency dividers (a digital circuit figure-of-merit for a device technology). To compete with advanced 100 nm SiGe processes, InP HBTs must be similarly scaled and high process yields are imperative. Described are several process modules in development -- these include an emitter-base dielectric sidewall spacer for increase yield, a collector pedestal implant for reduced extrinsic C,cb, and emitter regrowth for reduced base and emitter resistances.