Broad tuning ultra low noise DROs at 10 GHZ utilising ceramic based resonators

This paper describes the design of very low noise, tunable, X band dielectric resonator oscillators (DROs) demonstrating phase noise performance of -135 dBc/Hz at 10 kHz offset. A variety of resonator configurations utilising BaTiO₃ resonators are presented demonstrating unloaded Qs from 10,000 to 30,000. These resonators are optimally coupled to the amplifiers for minimum phase noise where Q_L/Q₀= 1/2 and S₂₁=-6 dB. SiGe transistors are used for the oscillator sustaining amplifiers which offer reasonable levels of circulating power ∼15 dBm and gains of 5.4 dB per stage as well as low flicker noise corners between 10 and 40 kHz. To incorporate tuning, with low additional phase noise, phase shift tuning is incorporated. The theory for the design is included demonstrating close correlation with experimental results.