Fuzzy Aided Phase Frequency Controlled Digital Phase Locked Loop

A new second order digital phase locked loop is proposed with an acquisition aid from a fuzzy logic controller. Here, control signal of Digitally Controlled Oscillator (DCO) is adjusted by loop filter in addition with a fuzzy logic controller which uses carrier phase and frequency error as input data. This addition helps the loop to perform exceptionally well to achieve the conflicting requirements of minimum acquisition time and maximum noise rejection. A further improvement towards this direction is noticed when the conventional DCO is equipped an additional phase control arrangement. The system level model of this proposed Fuzzy aided phase frequency controlled DPLL is implemented on a reconfigurable logic platform using system generator®, a tool from Xilinx® used for FPGA design. The improved ability of this proposed loop to track a frequency offset input is presented. A significant enhancement in noise squelching property is also demonstrated for demodulation of a single tone FM in presence of Additive White Gaussian Noise (AWGN).