Microwave Journal

Characteristics of E-pHEMT vs. HBTs for PA Applications

February 9, 2011


Many different semiconductor technologies are currently being used for power amplifiers (PAs) that include a mix of Silicon and GaAs devices—Silicon Bipolar, Silicon MOSFET, GaAs MESFET, GaAs HBT, and GaAs pHEMT. Avago uses an enhancement-mode pHEMT (E-pHEMT) process for its PA design while most competitors have developed GaAs HBT technology. This paper shows why E-pHEMT technology can provide superior electrical and reliability performance for power amplifier design in wireless communications.

Electrical Performance

Low battery leakage current consumption - Historically, leakage current has not been a strength of E-mode FET devices. However, Avago’s PAs using E-pHEMT technology have a very low drain-source current (Idss) of less than 10 μA at room temperature. This performance has been achieved through using a buried gate, correct crystal orientation, reducing the second recess depth, and optimizing the InGaAs channel with a selective etch process.