Phase locked loop

Details Phase locked loop Phase locked loop

2006-11-21

2006-11-21

Callahan, Timothy P. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Synchronizing

C375S374000

Reexamination Certificate

active

07138838

ABSTRACT:
A variable loop bandwidth phase locked loop in which, upon input of a succession of signals “1”, no modulated signal degradation occurs and even at a high symbol rate, the reference signal frequency remains low and the sampling frequencies of a phase-frequency detector and a sigma delta circuit remain low. The phase locked loop comprises: a first modulator which transforms baseband signal TX_DATA into an integer signal for specifying a division number and sends it to a control terminal of a programmable divider; a second modulator which shapes an incoming baseband signal into a prescribed signal waveform and sends it to a voltage controlled oscillator; and a variable current charge pump which changes the loop bandwidth of the phase locked loop according to control signal CUR.

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