Ceramic coaxial resonator oscillators
are fixed or narrowband tunable
oscillators based on high Q ceramic
resonators. The resonator is a silverplated
length of temperature-stable
ceramic shorted on one end. Using
these resonators in a negative resistance
oscillator configuration, phase
noise of better than –120 dBc/Hz at
10 kHz is now commercially available
up to 4 GHz. Coaxial resonator oscillators
(CRO), however, offer a practical
low cost solution for frequencies
between 1 and 5 GHz