Temperature-compensated frequency discriminator based on dielectric resonator

A planar circuit realisation of the Pound-type frequency discriminator has been implemented with a dielectric resonator in a microstrip environment. By taking advantage of the nature of the planar geometry, the circuit is further simplified and the original performance is maintained. Various frequency discriminators with centre frequencies around 4.2 GHz have been constructed and tested. It is demonstrated with analytical models and substantiated by measurement results that the dielectric resonator, with its own temperature coefficient of the resonant frequency, offers a degree of freedom that proves to be effective for temperature compensation in the design of the frequency discriminator. A temperature coefficient of 3.6 ppm/°C for the centre frequency is achieved with readily available dielectric resonator and substrate material from commercial sources. Further improvement of the system thermal stability can be obtained by tailoring the thermal property of the dielectric resonator to the chosen microstrip substrate.