A V-Band Parallel-Feedback Oscillator With a Micromachined Cavity Integrated on a Thin-Film Substrate

This letter presents a V-band cavity oscillator based on a thin-film substrate with a flip-chip interconnection. A cavity serves as a parallel-feedback element, which is fabricated using a micromachining technique and is flip-chip mounted on a thin-film substrate with integrated passives. A GaAs pseudomorphic high electron-mobility transistor is flip-chip mounted on the thin-film substrate as an active device to generate negative resistance. The fabricated cavity with I/O ports in the same side has a loaded Q of 352, a coupling of 5.3 dB, and a resonant frequency of 59.88 GHz. The developed parallel-feedback cavity oscillator has an output power of about 9.7 dBm and a low phase noise of ${-}112$ dBc/Hz at 1 MHz offset with an oscillation frequency at 59.84 GHz. This work allows a low-cost mm-wave frequency source with high performances.