The Effect of Collector Region Design on Large-Signal Performance of Horizontal Current Bipolar Transistor (HCBT)

The impact of collector region design on large-signal performance of horizontal current bipolar transistor (HCBT) technology is investigated by calibrated time-domain load-pull measurements. Three representative high-performance devices of the same geometry but with different collector doping profiles, namely, uniform, n-well, and low-doped, are subjected to large-signal measurements wherein the radio frequency (RF) time-domain waveforms of current and voltage are measured to facilitate the determination of the maximum output power for each device. The extensive measurements outline the boundaries of the maximum collector current and voltage swings at RF determining linear operating area, which are a result of the physical phenomena in the high-current and high-voltage regimes, namely, the Kirk effect and impact ionization, respectively. While the highest-doped n-well HCBT provides the highest output power of 25.3 dBm at 1-dB gain compression, and the lowest-doped HCBT enables a wideband match at the collector, the HCBT with a uniform doping profile provides a tradeoff between the output power and bandwidth of the output match. The results show the versatility of HCBT technology as an alternative to CMOS and/or sillicon–germanium (SiGe) large-signal RF circuits for the front-ends (FEs) in the sub-6 GHz wireless communications range.