E-pHEMT (enhancement-mode high-electron mobilitytransistor) is a semiconductor process optimized forwireless applications that operates from a singlepositive voltage source. Ordinary depletion-modepHEMTs conduct at zero gate bias, or when the draincurrent, Id, reaches a saturated level (Idss) at a gate-source voltage (Vgs) of 0 VDC. An E-pHEMT shows noconduction at zero gate bias, so that Id = 0 at Vgs = 0V. Thus, it can operate without the negative voltage(required for switch on) required for depletionmodedevices. Other gallium arsenide metalsemiconductorfield effect transistors (GaAs MESFET—also simplycalled GaAs FETs) and high-electron-mobilitytransistors (HEMT) also operate from a positivevoltage supply and require a negative voltage to turnon. The added components required to provide thenegative voltage increase system cost, take up valuableboard space and require extra design effort.Development of E-pHEMT Technology White Paper Avago’s E-pHEMT technology Santa Clara wafer fabrication location. During the E-pHEMT (enhancement-mode high-electron mobility last four years, Avago has focused its epitaxial and transistor) is a semiconductor process optimized for wafer development talents and resource on the wireless applications that operates from a single fabrication of four-inch PHEMT wafers. This is in positive voltage source. Ordinary depletion-mode contrast to other companies where E-pHEMT was pHEMTs conduct at zero gate bias, or when the drain only one of two or three candidates for potential use current, Id, reaches a saturated level (Idss) at a gate- in cellular handset power amplifiers. sou……