High performance SiGeC HBT integrated into a 0.25 μm BiCMOS technology featuring record 88% power-added efficiency

This paper reports on the power performance of RF high-breakdown voltage (>16.5 V) SiGeC HBT power devices, which have been successfully integrated into a BiCMOS platform featuring 0.25 μm CMOS and a full set of high-quality passives. These devices have an excellent tradeoff between power gain and breakdown voltage. The high speed combined with low parasitic elements enables over 80% power-added efficiency (PAE) and corresponding power gains (G_p) of 18 dB and higher over a relatively wide range of power densities. A peak performance of 88% PAE and 20 dB G_p is obtained at 0.25 W continuous-wave output power with a 792 μm emitter length device (396 μm² emitter area) operating at 1.8 GHz with 3.3 V supply voltage. Excellent power scaling versus emitter area is obtained. Measured output power shows an ideal increase of 3 dB when doubling the area. Also the corresponding matching scales. This is achieved by minimizing parasitic elements using deep trench isolation and careful design of the metal wiring. Furthermore, the base and emitter doping profiles are tuned to minimize the temperature dependence of the power gain. In combination with the high PAE, no effect of self-heating on power scaling is found.