A novel band-selective DGS configuration and its application to design of 5.8GHz oscillator

In this paper, a novel DGS(Defected Ground Structure) of band-selecting type and its application to oscillator are presented. The proposed DGS is composed of the defects on the metallic ground plane and the coupling gap on the top signal line. The coupling gap works a role such like a series capacitor at the band-pass resonator. As the suggested DGS is the structure for mounting an active device, it is the roles of a feedback loop as well as a frequency-selective circuit. The equivalent circuit parameters of the DGS are extracted by using a threedimensional EM simulation and simple circuit analysis method. As the application to a new DGS, we designed and fabricated the oscillator at 5.8GHz. The experimental results show 4.17 dBm output powers with over 22% dc-to-RF power eficiency and -85.8 dBc/Hz phase noise at 100 kHz offset from the fundamental carrier at 5.81GHz.