Browse Prior Art Database

Digital Phase Error Detector

IP.com Disclosure Number: IPCOM000052078D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Taber, J: AUTHOR

Abstract

In a phase-locked loop system a phase detector is used to determine the phase difference between the reference signal and the variable frequency clock. In the system disclosed herein, the variable frequency clock operates at an integer multiple of the reference signal.

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Digital Phase Error Detector

In a phase-locked loop system a phase detector is used to determine the phase difference between the reference signal and the variable frequency clock. In the system disclosed herein, the variable frequency clock operates at an integer multiple of the reference signal.

The mechanism disclosed herein departs from previous methods in that the input reference signal phase is altered to be synchronous with the variable frequency clock. The phase error accumulates until the total phase error causes the synchronized reference signal transition to occur before or after the reference phase of the clock.

The period of each phase of the clock is 1/NR, where N is the integer multiple and R is the reference channel transition rate.

When this occurs, an adjustment is made to both the variable frequency clock and the reference phase. Finally, the output of the phase detector is a synchronous digital signal. In Fig. 1, Example A, at (A) the following inequality has been satisfied.

See Original.

This indicates that the variable frequency clock is SET FAST. At A in the timing diagram, the reference phase is advanced and the frequency of the variable frequency clock is reduced. In Fig. 1, Example C at B this inequality has been satisfied See Original. where N = integer multiple See Original.

This indicates that the variable frequency clock is set slow. At(; See Orig the timing diagram, the reference phase is retarded and the frequency of the variable f...