An analytical approach of minimizing VCO phase noise

Low noise signal sources are crucial for the development of high bit rate wireless link multi-standard system such as point-to-point radios or multipoint radios. Since the VCO is one of the key contributors to overall phase noise performance, it is important to reduce its contribution as much as possible. This paper presents an analytical method to optimize the noise with which it is possible to determine the component parameters that mostly affect the phase noise performance for a given topology. The optimization technique is demonstrated through a design example, leading to ultra low noise VCO at 1 GHz. The design approach is not limited to this frequency, and can be extended to other higher frequency band. The measured phase noise at 10 kHz offset is better than -125 dBc/Hz, which agrees with the calculated and simulated values within 3 dB.