Iranian Journal of Electrical and Electronic Engineering

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Abstract— This paper presents a novel approach to obtain fast locking PLL by embedding a nonlinear element in the loop of PLL. The nonlinear element has a general parametric Taylor expansion. Using genetic algorithm (GA) we try to optimize the nonlinear element parameters. Embedding optimized nonlinear element in the loop shows enhancements in speed and stability of PLL. To evaluate the performance of the proposed structure, various tests performed and results compared with standard phase locked loop. The tests and results show the superior performance of the proposed PLL.

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Due to the nonlinear nature of the Bang-Bang phase-locked loops (BBPLLs), its transient analysis is very difficult. In this paper, new equations are proposed for expression of transient behavior of the second order BBPLLs to phase step input. This approach gives new insights into the transient behavior of BBPLLs. Approximating transient response to reasonable specific waveform the loop transient time characteristics such as locking time, peak time, rise time and over shoot are derived with acceptable accuracy. The validity of the resulted equations is verified through simulations using MATLAB SIMULINK. Simulation results show the high accuracy of the proposed method to model BBPLLs behavior.