Impact of indirect stability on phase noise performance of fully-integrated LC tuned VCOs

The phase noise of a VCO integrated in a RF receiver, fabricated in high-speed bipolar technology is studied in detail. The limitations arising from the AM-to-PM noise conversion and the indirect stability of the circuit have been addressed, introducing experimental and simulation procedures for their assessment. We show that the sources of low-frequency noise, usually neglected, due to these effects become instead important and limit the VCO phase noise performance.