A BURIED-CHANNEL SELF-ALIGNED GAAS-MESFET WITH HIGH POWER-EFFICIENCY AND LOW NOISE-FIGURE FOR 1.9-GHZ SINGLE-CHIP FRONT-END MMICS

We report on 1.9-GHz performance of the Buried-Channel self-aligned WN /W-gate GaAs MESFET (BC-MESFET) for use in digital mobile telephone ha ndsets with low power consumption. The BC-MESFET incorporates undoped i-GaAs epitaxial-grown surface layer on the ion-implanted channel. Bot h the power and noise performance of the BC-MESFET are superior to the conventional MESFET. The 0.6-mu m gate power BC-MESFET exhibits a hig h power-added efficiency of 57% at I-dB gain compression, which leads to low power dissipation of the handset. This power performance is att ributed to high breakdown voltage which the undoped i-GaAs surface lay er has brought about. The BC-MESFET has also shown a minimum noise fig ure of below 0.4 dB. Taking the IC-oriented fabrication process of the BC-MESFET into consideration, these FET performances demonstrate that the BC-MESFET is suitable for the single-chip MMIC that integrates RF front-end blocks for the 1.9-GHz small-size mobile telephone handset with long battery lifetime.