Design of Low Phase Noise RF Oscillators for Modern Wireless Communication Systems /

Abstract

In this work, a low phase noise RF oscillator is designed, simulated and measured. The size of the designed oscillator is compact enough to be used in different applications. Moreover, it can be designed with low fabrication facilities. First, a novel quad spiral resonator is designed. Two resonator structures were introduced. One with a wide separation between the spirals, and another with a narrow gap. Parametric analyses were performed on many physical parameters of the two structures. Different orientations were simulated and compared with each other until the one that gives the best performance was chosen. Another parametric sweep is done on the minimum dimension length, width, and separation used. Each dimension gives a resonator with its own oscillation frequency that can be used according to the desired application. The proposed resonator is compared with other published work and shows a significant improvement in the Q factor of about 400. Second, a negative resistance method is utilized in designing two oscillators, including nonlinear Harmonic Balance simulation, EM-Circuit-Co-simulation. The active device used in the proposed oscillators is ATF-13786. A biasing network as well as an output circuit are designed and optimized for both oscillators. The first oscillator works at 14.4 GHz with a low phase noise of -125 dBc/Hz @ 1 MHz. It has an output power of 10.6 dBm. The second is a harmonic oscillator at 20 GHz. The active circuit is designed to oscillate at 10 GHz, but the output circuit is matched to the second harmonic. The circuit oscillates at 19.8 GHz with a low phase noise of -101 dBc/Hz @ 10 KHz The circuit has an output power -3 dBm. The two circuits are compared with other published work in the same frequency range. The advantage of low phase noise is achieved at the expense of the area.