Trade-offs between SiGe and GaAs bipolar ICs

The intrinsic physical properties and electrical parameters of SiGe and GaAs heterojunction bipolar transistors (HBTs) are compared and discussed. The reported performance of the two devices are comparable. At the same but relatively low current densities, GaAs HBTs are faster than SiGe HBTs. However, SiGe HBTs not using SOI can be designed to operate at much higher current densities by using smaller emitters, resulting in much lower power dissipation and potentially higher performance, but larger substrate-coupling noise, than GaAs HBTs