Wide-range microwave frequency synthesis using an offset passive resonator

We demonstrate a technique to obtain wide synthesized tunability from the local oscillator (LO) of a low-noise, fixed-frequency microwave reference whose noise is suppressed by a high-Q cavity discriminator operated in a passive mode. The results show that under proper conditions the phase-locked LO´s phase noise in the tunable approach presented here and that for the normal fixed-frequency mode are substantially the same. Thus the need for a number of filters, mixers, and amplifiers necessary for an additional synthesizer is eliminated.