Traditional compound semiconductor HBT technologies do not allow for the independent design of the intrinsic and extrinsic collector regions commonly found in Si BJT and SiGe HBT technologies. By using a selectively implanted buried sub-collector (SIBS) to optimize the intrinsic collector for reduced transit time and extrinsic collector for reduced capacitance, InP DHBTs technologies can finally have the same flexibility. An improved 200 GHz InP DHBT technology for broadband amplifiers with good forward Gummel characteristics and a DC current gain exceeding 100 is presented. SIBS also allows the fabrication of two types of HBTs, one with a peak f(T)/f(MAX) of 208 GHz/225 GHz at I-C = 26.2 mA and one with a peakf f(T)/f(MAX) of 148 GHz/237 GHz at I-C - 16.6 mA, on a single water, giving tile circuit designer additional flexibility. A state of the art traveling wave amplifier with a 61 GHz 3 dB-bandwidth, 29 dB differential gain, and only 2.5 W total power dissipation is presented. At a 45 Gb/s data rate, a I I V differential output swing is demonstrated while maintaining < 0.3 ps of added RMS jitter and 8/8 ps rise/fall times. Compared to a traditional mesa technology, the SIBS technology increased the differential output voltage swing by 1.0 V. (c) 2006 Elsevier Ltd. All rights reserved.