Design and fabrication of a wideband 56-to 63-GHz monolithic power amplifier with very high power-added efficiency

This paper describes the design, fabrication, and measurement of a wideband 60 GHz monolithic microwave integrated circuit (MMIC) power amplifier that has demonstrated via on-wafer continuous wave (CW) measurement a record 43 % power-added efficiency (PAE) at an associated output power of 224 mW and 7.5 dB of power gain. At a higher drain bias of 3.5 V, the CW output power increased to 250 mW with 38.5% PAE. Additional performance improvement is e xpected when the MMICs are tested on-carrier with proper heat sinking. Thes e state-of-the-art first-pass design results can be attributed to: 1) the u se of a fully selective gate recess etch 0.12-mu m InP HEMT process fabrica ted on 2-mm-thick 3-in diameter InP substrates with slot via holes; 2) a de sign based on a novel on-wafer load-pull measurement technique; and 3) an a ccurate large-signal nonlinear model for InP HEMTs. In order to reach the l ow cost required for mass production, the same MMIC design was fabricated o n an InP metamorphic HEMT (MHEMT) process. The MHEMT version of the MMIC de monstrated 41.5% PAE, with an associated output power of 183 mW (305 mW/mm) and 6.9 dB of power at 60 GHz when measured CW on-wafer. These InP HEMT an d MHEMT results are, to our knowledge, the highest PAE and power bandwidth ever reported at V-band.