Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Synchronizing
Patent
1993-03-18
1995-03-21
Sikes, William L.
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Synchronizing
327237, 327553, H03K 513, H03L 718, H03L 7087, H03L 7089
Patent
active
053999851
ABSTRACT:
The invention provides a digital PLL circuit wherein the integration time constant of a random walk filter can be varied adaptively in response to a frequency error. A master clock signal having a frequency equal to N (integral number) times that of an input clock signal is normally divided by N by a divider, and the division output of the divider and the input clock signal are compared in phase with each other by a phase comparator. The dividing ratio of the divider is temporarily varied in accordance with a result of the comparison so as to make the phases of the division output and the input clock signal coincide with each other to establish synchronism between them. A variable step number random walk filter is interposed between the phase comparator and the divider and has a selectively settable integration time constant, and an integration time constant setting circuit varies the step number of the random walk filter in accordance with information of a last phase controlling direction or directions and information of a phase controlling direction at present to vary the integration time constant of the random walk filter.
REFERENCES:
patent: 4577163 (1986-03-01), Culp
patent: 4791386 (1988-12-01), Shiga
patent: 5015970 (1991-05-01), Williams et al.
patent: 5077529 (1991-12-01), Ghoshal et al.
Awata Yutaka
Kakuishi Mitsuo
Koizumi Nobukazu
Ohtomo Yasuo
Abraham Fetsum
Fujitsu Limited
Sikes William L.
LandOfFree
Digital PLL circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Digital PLL circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Digital PLL circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1151774