Abstract

This paper describes InGaP/GaAs/AlGaAs power DHBTs with the enhanced linearity near saturation output regions. The DHBT, having compositionally graded AlGaAs collector layers with a -doped layer, effectively improved the nonlinearity of the base-collector capacitance near the knee voltage and, consequently, reduced the distortion at near saturated output power levels. The power DHBT achieved an improvement in linear output power and PAE of 0.7 dBm and 2.5%, respectively, compared to the conventional SHBT, and exhibited an output power of 21.1 dBm and a PAE of 33.5% at an EVM of 5%, measured with 54Mbps 64-QAM-OFDM signals of 5.25 GHz at a supply voltage of 3.3 V.