This talk examines phase-noise origins and mitigation in oscillators that replace bulky spiral inductors and noise-degrading varactors with tunable active inductors (TAIs) synthesized via gyrator networks. Building on and extending Leeson-type models, Dr. Rohde presents closed-form treatments that capture active-device noise (shot/flicker) and large-signal effects, then validates the analysis on a ~1.9 GHz Colpitts using high-ft SiGe HBTs. Practical circuits demonstrate that self-injection locking with a phase-shift network can improve phase noise by ~8–10 dB while preserving tunability. The results position TAI-based VCOs as compact, integrable, and cost-effective alternatives for RF/MW systems, with next steps aimed at wider tuning range, enhanced dynamic range, and monolithic integration for filters, resonators, and phase-agile modules.
Noise in Oscillators with Active Inductors
MTL Special Seminar
Ulrich L. Rohde, Visiting Scientist at MIT Microsystems Technology Laboratories
Abstract
Bio
Prof. Dr. Ing. habil. Ulrich L. Rohde, IEEE Life Fellow, is partner of Rohde & Schwarz, Germany and Chairman of Synergy Microwave Corp., Paterson, NJ. Dr. Rohde is a Visiting Scientist at MIT Microsystems Technology Laboratories, a full professor of Radio & Microwave Theory & Techniques at the University of Oradea and honorary professor at several other universities worldwide: Prof. of Microwave Technology at IIT-Delhi, Chair Professor for Microwave Technology at IIT-Jammu, Professor of Microwave and RF at the BTU Cottbus-Senftenberg University of Technology, and professor at the German Armed Forces University Munich (Microwave Systems, Technical Informatics.).