High-efficiency and low-distortion directly-ion-implanted GaAs power MESFETs for digital personal handy-phone applications

We report a high-efficiency and low-distortion GaAs power MESFET using direct ion implantation technology for the digital wireless personal handy-phone system (PHS). When qualified by 1.9-GHz /spl pi//4-shifted quadrature phase shift keying (QPSK) modulated PHS standard signals, the 2.2-V-operation device with a gate width (Wg) of 2 mm exhibited a power-added efficiency (PAE) of 57.2 % and an adjacent channel leakage power (P/sub adj/) of -58 dBc at an output power of 21.3 dBm. The MESFET with the optimized direct ion implantation conditions and fabrication process achieved the highest PAE for PHS applications. The low-cost MMIC-oriented direct ion implantation technology has demonstrated the state-of-the-art results for new-generation PHS handsets for the first time.