Theoretical and experimental implementation of microwave active filters using automatic frequency control techniques

摘要

The paper discusses phase locked loop (PLL) and magnitude locked loop (MLL) techniques based on voltage controlled filter (VCF), for the automatic frequency control (AFC) of active filters. Applications to a microwave planar filter are considered. Theoretical analysis, simulated and measured results are presented for both phase and magnitude control circuits enabling the filter to accurately track a reference signal.