MEMS Chip With Amplifier for 4-W Power Combining up to 100 GHz

Millimeter-wave and terahertz bands are very attractive for high-resolution radars and fifth-generation communication and beyond; nevertheless, it is very challenging to achieve high output power in silicon. To address this crucial issue, this article first presents an in-house developed silicon micromachining process. Using this process, a power combiner is formed in silicon waveguide, by dry etching and bonding two 8-in silicon wafers. Benefiting from the hollow, symmetrical, and accurately assembled waveguide structure, the power combiner features a measured low loss of 0.2 dB and a high amplitude/phase balance of +/- 0.15 dB/+/- 2 degrees from 92 to 96 GHz. Moreover, based on this power combiner and an in-house fabricated power amplifier in gallium nitride (GaN), this article further demonstrates a power combing prototype with a typical output power of 4 W, a power-added efficiency of higher than 12.9%, and a combining efficiency of higher than 92%.