High-efficiency millimeter-wave GaAs/GaAlAs power HEMT´s

The power, gain, and efficiency of 0.5-µm gate-length, 75- and 50-µm gate-width multiple heterojunction high electron mobility transistors (HEMT´s) have been evaluated from 10 to 60 GHz. At 10 GHz, with a source-to-drain voltage as low as 2.4 V, the device delivers a power density of 0.37 W/mm with 13.4-dB gain and 60.8-percent efficiency. At 60 GHz, a 50-µm device gave 0.4 W/mm with 3.6-dB gain and 14-percent efficiency. The power density and efficiency of these 0.5- µm gate-length HEMT´s above 40 GHz are the best reported for a three-terminal device. Fundamental frequency oscillations up to 104 GHz were observed when a device was bonded as a free-running oscillator.