Nonlinear acceleration of phase locked loops

A simple nonlinear algorithm is examined which significantly enhances the signal acquisition and tracking performance of second-order phase-locked loops (PLLs). This algorithm is significant in that it reduces the signal acquisition time of an otherwise conventional loop by a factor of up to several thousand while enabling a narrowband PLL to remain locked onto very-high-dynamics signals without switching loop bandwidths or increasing the loop order. It is shown that the phase noise is improved as compared to a PLL having an equivalent wider bandwidth. These improvement factors in acquisition time and dynamic tracking, as well as the tradeoffs in phase noise performance, are examined through explicit analysis and computer modeling