Ultra low noise low cost octave-band hybrid-tuned VCO

The application where coarse and fine-tuning is prime requirement, phase noise gets drastically degraded in presence of the fine tuning network if incorporated with a coarse tuning network. A VCO with a frequency that is less sensitive to tuning control voltage fluctuations imparts less phase jitter to the system, but suffers from a narrower tuning range, thereby it is limited by tuning band. This paper describes the unique approach of the hybrid tuning capability of the octave-band VCO (1000-2000 MHz/2000-4000 MHz) without sacrificing the phase noise and the tuning range. The design is based on innovative topology, which supports the fast convergence by using coarse-tuning and fine adjustments, by fine-tuning network. The measured phase noise is better than -103 dBc/Hz @ 10 kHz offset for the frequency band 1000-2000 MHz