RF CHARACTERISTICS OF GAAS POWER MESFETS WITH SUPERLATTICE BUFFER LAYER

A GaAs power MESFET with a GaAs/AlGaAs superlattice buffer layer has b een developed for high efficiency and low distortion. The power MESFET has a low-high doped channel structure and it is fabricated using the standard process of GaAs power MESFET. The effects of the buffer stru ctures on efficiency and linearity of the power MESFET's are investiga ted by analyzing the transconductance and drain conductance dependent on gate bias, drain bias, and frequency through the I-V and S-paramete r measurements. The power MESFET with the optimized superlattice buffe r shows output power of 1 dB higher than that with an undoped buffer l ayer. It shows efficiency increment of 3% and third-order intermodulat ion (IM3) reduction of 3 dB compared to the MESFET with the undoped bu ffer layer.