HBT oscillator employing a slot coupled sapphire resonator to achieve low phase noise performance

A heterojunction bipolar transistor (HBT) MIC oscillator stabilized by a novel slot coupled sapphire resonator (SCSR) is reported. Common base mode device operation is utilized, transistor destabilization being achieved via series inductive feedback between base and ground. The SCSR, which has an unloaded Q-factor of 2500, is reaction coupled to the emitter circuit of the HBT to facilitate frequency stabilization. Single sideband (ssb) phase noise performance for the topology of −58dBc/Hz and −92dBc/Hz has been achieved at offset frequencies of 1KHz and 10KHz respectively from the oscillator carrier frequency of 6.40GHz.