Computer-Aided Pull-In Range Investigation of Microwave PLL

An important parameter which characterizes the dynamic behaviour of the phase-lock loop is its pull-in range. This quantity is highly affected, especially at microwave frequency bands, by the transportation lag inherently present in the loop. A nonlinear model of the phase-lock loop has been used to investigate the effect of the phase detector characteristic, tuning characteristic of the voltage-controlled oscillator, the loop filter transfer function and the transportation lag on the pull-in range. The results of computer simulations are in good agreement with experiments performed with an X-band second-order phase-lock loop incorporating a phase detector with sinusoidal, triangular, or saw-tooth characteristic and a variable delay line.