Analysis of a MEMS Tuned Cavity Oscillator on X-Band

This paper reports on the analysis of a radio frequency microelectromechanical systems (RF-MEMS) tuned cavity oscillator on X-band based on a GaN-HEMT monolithic microwave integrated circuit reflection amplifier. The RF-MEMS-switches are mounted on a low-loss printed circuit board (PCB) intruded in an aluminum cavity that is coupled to a microstrip line connected to the reflection amplifier. This paper investigates the influence of the number of switches as well as their positions with respect to phase noise and tuning range. Vertical and horizontal positions of the switches are varied with target on optimum trade-off between phase noise and total tuning range. For a three-row MEMS-configuration at 1-mm depth from the end cavity wall, a tuning range of 4.9% is measured. The center frequencies are ranging from 9.84 to 10.33 GHz with measured phase noise of -140 to -129 dBc/Hz at 100-kHz offset. A similar three-row MEMS setup at 2.5-mm depth provides a tuning range of 12.3% with measured phase noise of -133 to -123 dBc/Hz at 100-kHz offset