dielectric resonator oscillator (DRO)
DRO oscillators(Dielectric Resonator Oscillator) operate in the microwave range and use dielectric resonators as resonators.
Due to the high quality factor of the dielectric resonator, they are characterized by lowest phase noise and a high frequency stability, which can be +/- 1 MHz in the frequency range between 1 GHz and 50 GHz. The temperature coefficient is extremely low, at a few ppm/°C.
Inconjunction with a capacitance diode, voltage-controlled DOR oscillators with a small tuning range, which can be +/- 1%, can also be constructed. To increase frequency stability and reduce phase noise, DOR oscillators can be coupled to high-precision crystal oscillators via phase-locked loops.