Enhanced dynamical response of derivative controlled third order phase locked loops

• Dynamics of phase locked loop with resonant filter is reported including derivative control.
• Modification leads to extended stable zone and better transient response.
• Modified structure requires minimum additional hardware.
• Improved loop dynamics is established through analytical, numerical and experimental results.

Dynamical responses of third order phase locked loops with resonant filters are examined by modifying the control signal applied to loop oscillator. Using signals obtained at some internal nodes of loop resonant filter, the control signal is modified. These signals are effectively single or double derivatives of normal control signal. Performances of modified loops are found to improve during transient and tracking modes of loop operation. This is established through analytical, numerical simulation and experimental studies. The dynamics of the loops in unstable self-oscillatory and aperiodic oscillating modes could also be controlled by these additional derivative control signals.