Phase-locked loop with variable bandwidth, has constant ratio of variable division values of frequency dividers provided in forward and feedback paths

摘要

The phase-locked loop has a forward path (12) and a feedback path (13). A first frequency divider has a variable division value (R) in the forward path. A second frequency divider has a variable division value (N) in the feedback path. A control unit (11) is provided for presetting the two division values, such that the ratio of the first value to the second value remains constant. A sigma-delta modulator (6) may be connected between the control unit and the second frequency divider.