On-Wafer Load-Pull Characterization of Self-Aligned GaAs Power MESFETs

A measurement system for on-wafer load-pull characterization of GaAs power MESFETs is described. High accuracy is obtained by using vector error-correction techniques. The usefulness and the limitations of the system are discussed. Ion implanted GaAs power MESFET cells with total gate widths up to 1.6 mm and differing gate finger widths were fabricated using a self-aligned DIOM technology. Measurements in the frequency range between 3 and 11.5 GHz showed a frequency independent 1 dB compressed output power of more than 0.65 W/mm for structures with a gate finger width of 100 ¿m and a gate length of 0.8 ¿m. These results are needed for optimization of the transistor layout for the frequency band of interest and for power MMIC designs.