Design of a low phase noise voltage tuned DRO based on improved dielectric resonator coupling structure

In this paper, we present a voltage tuned dielectric resonator oscillator (Vt-DRO) with a low phase noise, which is achieved by improving the coupling structure between the dielectric resonator and microstrip line. The Vt-DRO is a closed-loop type and is composed of 3 blocks; dielectric resonator, phase shifter, and amplifier. By modifying the coupling structure between the dielectric resonator and microstrip line, we achieved a group delay of about 53 nsec. The closed-loop Vt-DRO was implemented by closing the designed open-loop. As a result, the phase noise of the Vt-DRO was measured as -132.7 dBc/Hz at 100 kHz offset frequency, which was close to the predicted value using the measured open loop group delay at 5.3 GHz. The tuning-range of the Vt-DRO is about 5 MHz for tuning voltage of 0-10 V and the power is 4.5 dBm.