W- and G-Band Solid State Power Combining

Recent advances in semiconductor technologies have enabled the design and fabrication of mmW MMIC amplifiers with unprecedented gain, output power, and power added efficiency. However, individual mmW MMIC performance is ultimately limited by transistor size and on-die power combining losses. Therefore, in order to achieve significant solid state mmW amplifier power levels, low-loss off-die power combining is obviously necessary. This paper examines trade-offs between on-die, waveguide, and spatial power combining approaches. Several examples of mmW power combined amplifiers are discussed including 10W+ W-band GaN and 1W-class EHF InP amplifiers.