Linearization of the first-order TDTL using a pre-distortion scheme

In this paper the architecture of a first-order time delay digital tanlock loop (TDTL) with linearized phase detector (PD) using a feedforward pre-distortion technique is proposed. The technique, which has been traditionally used with power amplifiers, involves pre-distorting the input signal to the TDTL so as to compensate for the nonlinearity of the TDTL caused by its fixed time delay unit. The performance of the proposed system was evaluated in noisy and noise-free environments and compared with the original TDTL system using sudden changes in input signal frequency using MATLAB/Simulink. In both cases, results indicate that the performance of the proposed TDTL with pre-distortion outperforms that of the original TDTL system.