Browse Prior Art Database

Deskewing System

IP.com Disclosure Number: IPCOM000091367D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Schaefer, WC: AUTHOR

Abstract

This circuit arrangement accommodates static skew of a large number of data bits for nominally concurrently appearing signals of a record. It is also effective on a dynamic skew where the record time is much less than the period of the dynamic skew.

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Deskewing System

This circuit arrangement accommodates static skew of a large number of data bits for nominally concurrently appearing signals of a record. It is also effective on a dynamic skew where the record time is much less than the period of the dynamic skew.

Data pulses are desired at output terminals 10A ...10N concurrently despite static skew interposed by components ahead of input terminals 11A...11N. A number of multiple-bit fixed delay elements 14 is connected in series between the input and output terminals of each line A...N. The number of elements 14 effective in each line is adjusted by effectively short-circuiting such elements with And's 16. Schmitt triggers 18, individual to And's 16, are responsive to the output voltage of ramp generators 20A...20N individual to the lines. Triggers 18 for each line are triggered at different successive levels of output voltage to which the associated ramp generator 20 rises for each record. Thus different values of delay are left remaining effective in the lines for skew accommodation. Generators 20 are all turned on simultaneously and turned off successively in order of skew through And's 22. Control of And's 22 is effected by normally down, line flip-flops 24, a normally up, interchannel flip-flop 26 and Or 28.

Single-bit fixed delay elements 34 are used to deskew further on a single bit basis. And's 36, operated by Schmitt triggers 38, serve to connect the proper number of elements 34 for exactly accommodating the skew. The level-setting voltages for operating triggers 38 are obtained from sawtooth wave generators 40, connected to generators 20. Generator 40B is shown in detail. The negative voltages a, b, c and d are increasingly negative and provide a low positive-going sawtooth wave for application to triggers 38.

Like pulse signals appearing on all lines at the beginning of each record for other requirements of the overall system, such as gain setting and the like, set the system for sk...