An X-band Cross-Coupled SIW Cavity VCO

We investigate the use of SIW resonators in cross-coupled VCOs. A rectangular, unloaded SIW cavity with external varactor loading at the ports is implemented, and applied to a SiGe HBT cross-coupled pair. A nominal f
_osc
of 11.6 GHz with 80 MHz tuning range is achieved through a combination of varactor and supply rail tuning. The single-ended output of the VCO produces an average of 1 dBm output power over the tuning range, with an average phase noise of -105 dBc/Hz at a 1 MHz offset.