Ka-Band high-power and driver MMIC amplifiers using GaAs PHEMTs and coplanar waveguides

We report the design and fabrication of compact 2- and 3-stage coplanar (CPW) microwave monolithic integrated circuit (MMIC) amplifiers having high output power at Ka-band. Based on a 0.15-æm gate length GaAs PHEMT process, a two-stage MMIC driver amplifier has demonstrated at 35 GHz, a linear gain of 11 dB, an output power at 1 dB gain compression P(-1)dB of 350 mW, and a saturated output power P(sat) greater than 500 mW. For the same frequency, the high-power CPW 2-stage amplifier achieved a linear gain of 9.5 dB, with P(-1) dB = 725 mW and more than 1 W of saturated output power. Additional thermal management resulted in an increased performance, namely, 10.4 dB linear gain, P(-1) dB = 950 mW and P(sat) = 1.2 W. To our knowledge, those are the highest output powers ever reported at Ka-band for any uniplanar MMIC