A reconfigurable high-frequency phase-locked loop

Reconfigurable phase-locked loops (PLLs) present the advantage of fast-frequency acquisition combined with narrow-noise bandwidth, since their parameters can be dynamically adjusted. High-frequency PLLs are generally implemented by means of analog circuits which are not easily reconfigured during operation. However, the fiveport technique allows the discrimination of the phase difference between two microwave signals using a mixed circuit. In this paper the design of a PLL comprising a five-port based phase detector is presented. This system benefits from the phasedetector digital circuit to carry out the loop filtering. Simulation results for different conditions of noise and frequency acquisition are shown. We also present measurement results to confirm the simulations.