A high lock-in speed digital phase-locked loop

A digital phase-locked loop (DPLL) consisting of a modified 9-gate phase detector, a frequency multiplier, and a loop filter is described. All the components are implemented in digital hardware. The Z-transform is employed to deduce the system function, and some simple properties of the DPLL are inferred by examining the mathematical model. The advantages of the proposed DPLL are: high lock-in speed, no steady-state frequency tracking error even for period ramp input signals; and ease of integration into a single chip. The use of the DPLL to realize the pitch synchronous analysis of voiced speech is reported