Alleviation of Thermal Instability via Novel Collector-Up HBTs for Reliable Wireless Applications

We analyzed thermal characteristics of power transistors based on the complementary InGaP/InGaAs/GaAs collector-up heterojunction bipolar transistors (HBTs), and especially for stable wireless applications under extreme operations. A newly developed structure, incorporating the graded InGaAs base and the nonuniform collector, without employing additional thermal-removal design is presented. Significantly, the multi-finger devices achieved compelling high speed and heat dissipation. Results show that the fairly matched high-frequency performance has been exhibited and over 30% improvement in the surface-temperature-rise ratio is achieved. As a consequence of the effective alleviation of unstable feedback phenomena by this novel arrangement, exploiting the advantageous characteristics of complementary collector-up HBTs for thermally reliable high-speed wireless applications is feasible.