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Browse Prior Art Database

Continuous-Phase-Adjustable Frequency Synthesizer

IP.com Disclosure Number: IPCOM000102831D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Griess, KR: AUTHOR

Abstract

Disclosed is a circuit that allows the phase relationship of two synched clocks (of same or different frequencies) to be manually adjusted in a continuous manner.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Continuous-Phase-Adjustable Frequency Synthesizer

      Disclosed is a circuit that allows the phase relationship of
two synched clocks (of same or different frequencies) to be manually
adjusted in a continuous manner.

      The circuit shown in the figure generates a clock FOUT that is
synched to clock FREF and whose phase relationship to FREF is
adjustable by potentiometer VR.  The potentiometer controls the width
of the negative-going pulse TW out of the Single Shot (SS) whose
rising edge is what the VFO (Variable Frequency Oscillator) synchs
to.  By increasing TW, FOUT is further delayed with respect to FREF.
Likewise, reducing TW advances the edges of FOUT with respect to
FREF.  The amount of adjustment of TW is determined by the value of
VR.  Since TW must return to an UP level before the next rising edge
of FREF, the variation of TW is limited to something less than 1
period of FREF. By dividing FREF by 2 before feeding it into the SS,
the amount of possible variation of TW is doubled.  The halving of
the frequency FREF DELAY can be compensated for by doubling N or
halving M, the internal counter values of the VFO.

      By choosing a potentiometer with very fine adjustment, very
precise phase relationships between FOUT and FREF can be established.
The precision would be a function of the transfer characteristics of
TW vs. VR (for a fixed value of C) and also of the total number
of turns.

      Disclosed anonymously.