Apparatus and method for high resolution frequency adjustment in a multistage frequency synthesizer

摘要

An apparatus and a method for making high resolution frequency adjustments in a multistage frequency synthesizer. The initial stage of the frequency synthesizer is a conventional phase lock loop connected to a dynamically variable frequency divider. There are one or more intermediate stages that consist of the forward portion of a phase locked loop with feedback through a fixed frequency divider and connected to a dynamically variable frequency divider. The final stage consists of the forward portion of a phase locked loop with feedback through a fixed frequency divider and connected to another fixed frequency divider. By varying the constant of division in the variable frequency dividers in the circuit, fine frequency adjustments can be made very rapidly. The precision of the adjustments depends on the relative values of the frequency dividers and the number of intermediate stages in the system.