Design and performance of dielectric resonator oscillators with series feedback

It is noted that series feedback oscillators stabilized with dielectric resonators (DRs) usually have the two resistive elements of the feedback network (DR and load) in different branches. A design technique for these oscillators is presented which leads to the maximum added power condition and optimization of frequency stability and noise immunity. The nonlinear characterization of the active device is obtained assuming an empirical relation to the power-gain saturation characteristics. The oscillator stability is verified by means of graphical methods based on the network determinant or and on the negative resistance oscillator theory of Kurokawa (1969). The six possible topologies are analyzed for a typical X-band GaAs MESFET using the proposed method. A comparison is made, taking into account the circuit implementation in microstrip, stability, AM and FM noise, spurious oscillations, transient response, and loaded Q-factor