This paper investigates the factors that influence the phase noise
performance of an oscillator and proposes a modified structure for improved
phase noise performance. A single and multiphase oscillator analysis using
the harmonic balance method is presented. The modified structure increases
the oscillation amplitude without increasing the bias current and leads to
improved phase noise performance as well as decreased power consumption.
The modification is analyzed and the figure of merit of the oscillator shows a
significant improvement of 21 dB. Numerical and analytical solutions are
presented to predict the oscillation frequency and phase noise. The analytical
solution is used to approximate the first harmonic and can be combined with
numerical simulations to extrapolate phase noise performance.