Efficient design approach for a SiGe HBT oscillator incorporating reflection sapphire loaded cavity resonator

This paper describes an efficient design approach for a ultra low phase noise SiGe heterojunction bipolar transistor (HBT) based sapphire loaded cavity (SLC) oscillator. Proposed design approach deals with the three-port microwave oscillator circuit incorporating reflection whispering gallery resonator (WGR) and it employs an open loop network extraction-analysis procedure for the oscillator circuit parameters calculation and accurate phase noise performance prediction. To demonstrate how a developed approach works a design procedure for the 4.596 GHz parallel and serial feedback SLC oscillator configurations is presented. A final discussion is devoted to the analysis and computer simulation of the oscillator phase noise performance. It is shown that a phase noise of the C-band SiGe HBT oscillator incorporating a reflection sapphire WGR can be as low as -152 dBc/Hz at 1 kHz Fourier frequency.