Design of microwave oscillators using linear, quasi-linear and nonlinear methods

In this paper, modern CAD techniques for simulating and designing microwave oscillators are surveyed. The analysis and design approaches of microwave oscillators are classified into three categories namely, linear, quasi-linear, and nonlinear. An applicable method is chosen from each approach to be implemented. These methods are used to design an 8.5 GHz microstrip oscillator. The results of these methods are entered to the “Microwave Design System” package, as initial designs. These designs are enhanced using the available optimization routines. The final optimized linear, quasi-linear, and nonlinear designs are compared using the most powerful nonlinear simulation and the transistor nonlinear model. From these simulations, the performance of each design method can be determined. It is found that the nonlinearly designed oscillator circuit is the most accurate one. This circuit is fabricated and measured. Excellent agreement between theoretical and experimental results is obtained