Comparison of injection locking techniques using nonlinear methods

An important element in the front end of a communication system is the local oscillator used for frequency translation. The local oscillator must be stable (i.e, low phase noise) for accurate processing of the information. One method of oscillator stabilization is injection locking. This work examines the various injection locking processes using nonlinear modeling techniques in the frequency and time domain. The frequency domain modeling employs the harmonic balance approach and uses a power series to model the nonlinear I-V relationship in the oscillator's active device. This analytical approach is utilized to derive equations for the various injection locking methods, such as fundamental, subharmonic, superharomic, parametric, and idler. This thesis is the first work to derive, using a common model, locking range equations for the different methods of injection locking oscillators. On the other hand, the time domain technique utilizes commercial software to predict the dynamic response of an injection locked oscillator. Libra[registered], a microwave circuit simulator from HP-EEsof, is used for the time domain prediction of forced oscillation. The time response is converted to the frequency domain using MATLAB[registered]. The MATLAB based signal processing method is applied to determine the free-running oscillator spectrum, the injection locking range of the different injection locking methods, and the oscillator phase noise. Data windowing is used to enhance the frequency domain resolution. A spectral resolution of -120 dBc/Hz at a 150 KHz offset is achieved with 1.4 million data points using an Ultra-SPARC2 processor. An oscillator has been designed, realized, and simulated at the UHF band using the time domain technique. The simulation results due used to extract the power series coefficients for the locking range equations. Comparison of analytical, numerical, and experimental performance is conducted in terms of locking range for different injection locking techniques. The simulated and experimental performance match well. The oscillator noise simulations compare well with the generally accepted Leeson's equation showing the potential of this method for the simulation of complicated circuits such as self-oscillating mixers.