Novel Methods for Phase Noise Reduction and Harmonic Suppression in a Planar Oscillator Circuit Based on Planar Helical Resonators

This paper describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in CPW technology. The high Q-factor and spurious-free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator showed a loaded Q of 180 in a chip area of only 40% of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed additional phase noise reduction of 10.5 dB at 1MHz offset and a second harmonic suppression enhancement of 6dB when compared to those of a conventional CPW oscillator without the PHR structure