EP0173521A2
Expired / Lapsed
EP
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Automatic signal delay adjustment apparatus
Assignee: Unisys Corp
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Filing: 1985-08-16
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Granted: —
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Expires: 2005-08-16
Abstract
Abstract A method and apparatus for automatically adjusting the propagation time delay of an electrical circuit, such as an integrated circuit chip. In a preferred embodiment, the method and apparatus are employed to de-skew the clock outputs provided by a plurality of clock distribution chips having different signal propagation times. In a preferred implementation of the method and apparatus, feedback circuitry including a multi-tapped delay line and an accurate constant delay are employed in conjunction with a phase comparator for automatically adjusting the propagation delay of each chip to provide substantially the same constant delay relative to a main system clock or the clock outputs provided by the clock distribution chips.
Inventors
- 👤 Laurence P. Flora
- 👤 Michael A. Mccullough
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 13:15
CPC Classifications
G; G06; G06F; G06F1/00; G06F1/04; G06F1/10; H; H04; H04L; H04L7/00; H04L7/02; H04L7/033; H04L7/0337
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
139 words
Electrical circuit means for automatically providing a desired propagation delay for an electrical circuit, said electrical circuit means comprising: delay means responsive to an input signal for producing a plurality of delayed signals having different delays relative to said input signal; means for applying a selected one of said delayed signals to said circuit; means for determining whether the propagation delay provided by a selected delayed signal is substantially equal to said desired propagation delay; means for automatically selecting a different delayed signal if the propagation delay provided by a currently selected delayed signal is determined not to be substantially equal to said desired propagation delay; and means for preventing selection of a different delayed signal when it is determined that the currently selected delayed signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 2
Dependent Claim
139 words
Electrical circuit means for automatically providing a desired propagation delay for an electrical circuit, said electrical circuit means comprising: delay means responsive to an input signal for producing a plurality of delayed signals having different delays relative to said input signal; means for applying a selected one of said delayed signals to said circuit; means for determining whether the propagation delay provided by a selected delayed signal is substantially equal to said desired propagation delay; means for automatically selecting a different delayed signal if the propagation delay provided by a currently selected delayed signal is determined not to be substantially equal to said desired propagation delay; and means for preventing selection of a different delayed signal when it is determined that the currently selected delayed signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 3
Dependent Claim
46 words
The invention in accordance with claim 1, wherein said means for preventing includes means for locking-in selection of a selected delayed signal when said means for determining indicates that a selected delayed signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 4
Dependent Claim
109 words
The invention in accordance with claim 1, wherein said circuit prouuces at least one output signal having a time relationship relative to said input signal which is indicative of the propagation delay of said circuit, wherein said means for determining includes means for deriving a comparison signal having a predetermined delay relative to said input signal, said predetermined delay being chosen based on said desired propagation delay, and wherein said means for determining also includes means for comparing the time relationship between said comparison signal and said output signal for determining whether the propagation delay provided by a selected delayed signal is substantially equal to said desired propagation delay.
Claim 5
Dependent Claim
39 words
The invention in accordance with claim 3, wherein said means for deriving a comparison signal includes a fixed delay to which said input signal is applied, said comparison signal being derived from the output signal from said fixed delay.
Claim 6
Dependent Claim
17 words
The invention in accordance with claim 4, wherein said fixed delay comprises a conductor of predetermined length.
Claim 7
Dependent Claim
16 words
The invention in accordance with claim 3, wherein said means for comparing includes a phase comparator.
Claim 8
Dependent Claim
69 words
The invention in accordance with claim 3, wherein said means for automatically selecting includes counting means, means for advancing said counting means in response to said means for determining indicating that the propagation delay provided by a selected delayed signal is not substantially equal to said desired propagation delay, and means for selecting another delayed signal for application to said circuit dependent upon the count of said counting means.
Claim 9
Dependent Claim
31 words
The invention in accordance with claim 7, wherein said means for automatically selecting includes multiplexor means responsive to the count of said counting means for selecting one of said delayed signals.
Claim 10
Dependent Claim
46 words
The invention in accordance with claim 7, wherein said means for selecting another delayed signal operates such that advancement of said counting means causes selection of a delayed signal having a larger delay relative to said input signal than that of the previously selected delayed signal.
Claim 11
Dependent Claim
18 words
The invention in accordance with claim 9, including means for setting said counting means to an initial count.
Claim 12
Dependent Claim
50 words
The invention in accordance with claim 9, wherein said means for preventing operates to prevent change of the count of said counting means in response to said means for determining indicating that a currently selected delayed signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 13
Dependent Claim
40 words
The invention in accordance with claim 9, wherein said means for preventing includes means for locking-in selection of a selected delayed signal when it is determined to provide a propagation delay which is substantially equal to said desired propagation delay.
Claim 14
Dependent Claim
23 words
The invention in accordance with claim 9, including means for producing an error indication when said counting means advances to a predetermined count.
Claim 15
Dependent Claim
28 words
The invention in accordance with claim 9, including means for producing an error indication when none of said delayed signals is able to provide said desired propagation delay.
Claim 16
Dependent Claim
16 words
The invention in accordance with claim 9, wherein said delay means comprises a multi-tapped delay means.
Claim 17
Dependent Claim
30 words
The invention in accordance with claim 9, wherein said delay means comprises a plurality of serially connected gates, and wherein said delayed signals are obtained from connections between said gates.
Claim 18
Dependent Claim
40 words
The invention in accordance with claim 3, wherein said electrical circuit is provided on an integrated circuit chip, and wherein said electrical circuit means for automatically providing a desired propagation delay for said circuit is also provided on said chip.
Claim 19
Dependent Claim
51 words
The invention in accordance with claim 17, wherein a plurality of said chips are provided, wherein said input signal is applied to each of said chips, and wherein said predetermined delay for each electrical circuit means is chosen so that the output signals from said circuit means have substantially no skew.
Claim 20
Dependent Claim
22 words
The invention in accordance with claim 18, wherein each chip is a clock distribution circuit and said input signal is a clock.
Claim 21
Dependent Claim
149 words
20 A method for automatically providing a desired propagation delay for an electrical circuit with respect to an applied input signal and an output signal to be produced thereby, said method comprising the steps of: producing in response to said applied input signal a plurality of input signals having different delays relative to said applied input signal; selecting one of said input signals for application to said circuit; determining whether the propagation delay provided by a selected one of said input signals is substantially equal to said desired propagation delay; automatically selecting a different one of said input signals if the propagation delay provided by a currently selected input signal is determined not to be substantially equal to said desired propagation delay; and repeating the steps of determining and automatically selecting until said determining determines that a currently selected input signal results in providing substantially said desired propagation delay.
Claim 22
Dependent Claim
149 words
20 A method for automatically providing a desired propagation delay for an electrical circuit with respect to an applied input signal and an output signal to be produced thereby, said method comprising the steps of: producing in response to said applied input signal a plurality of input signals having different delays relative to said applied input signal; selecting one of said input signals for application to said circuit; determining whether the propagation delay provided by a selected one of said input signals is substantially equal to said desired propagation delay; automatically selecting a different one of said input signals if the propagation delay provided by a currently selected input signal is determined not to be substantially equal to said desired propagation delay; and repeating the steps of determining and automatically selecting until said determining determines that a currently selected input signal results in providing substantially said desired propagation delay.
Claim 23
Dependent Claim
41 words
The invention in accordance with claim 20 including the step of preventing selection of a different input signal when it is determined that the currently selected input signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 24
Dependent Claim
41 words
2 2 . The invention in accordance with claim 21 wherein the step of preventing includes locking-in selection of a selected input signal when it is determined to provide a propagation delay which is substantially equal to said desired propagation delay.
Claim 25
Dependent Claim
48 words
The invention in accordance with claim 20 wherein the step of determining includes comparing the time relationship between a first signal derived from said output signal and a second signal derived by delaying said applied input signal by a predetermined amount chosen based on said desired propagation delay.
Claim 26
Dependent Claim
55 words
The invention in accordance with claim 20 wherein the step of automatically selecting includes advancing a counter in response to the step of determining indicating that the currently selected input signal does not provide said desired propagation delay and selecting another input signal for application to said circuit dependent upon the count of said counter.
Claim 27
Dependent Claim
29 words
The invention in accordance with claim 2 4 wherein said selecting is arranged such that advancement of said counter increases the propagation delay provided by the selected input signal.
Claim 28
Dependent Claim
31 words
2 6. The invention in accordance with claim 25 including the step of setting said counter to an initial count prior to application of a selected input signal to said circuit.
Claim 29
Dependent Claim
53 words
27 . The invention in accordance with claim 25 wherein the step of determining includes comparing the time relationship between a first signal derived from said output signal with a second signal having a predetermined delay relative to said applied input signal, said predetermined delay being chosen based on said desired propagation delay.
Claim 30
Dependent Claim
44 words
28 . The invention in accordance with claim 27 including the step of preventing further advancement of said counter in response to said determining indicating that a currently selected input signal provides a propagation delay which is substantially equal to said desired propagation delay.
Claim 31
Dependent Claim
41 words
29 . The invention in accordance with claim 2 8 wherein tne step of preventing includes locking-in selection of a selected input signal when it is determined to provide a propagation delay which is substantially equal to said desired propagation delay.
Claim 32
Dependent Claim
23 words
The invention in accordance with claim 25 including the step of producing an error indication when the counter advances to a predetermined count.
Claim 33
Dependent Claim
29 words
The invention in accordance with claim 25 including the step of producing an error indication when none of said input signals is able to provide said desired propagation delay.
Claim 34
Dependent Claim
34 words
The invention in accordance with claim 27. wherein said method is employed for providing each of a plurality of said circuits with a propagation delay which is substantially equal to said desired propagation delay.
Claim 35
Dependent Claim
14 words
The invention in accordance with claim 32 wherein said circuits are clock distribution circuits.
Claim 36
Dependent Claim
20 words
The invention in accordance with claim 32 wherein each of said circuits is implemented on a different integrated circuit chip.
Claim 37
Dependent Claim
28 words
The invention in accordance with claim 34 wherein said method includes providing circuitry on each chip for implementing the steps of producing, selecting, determining, automatically selecting and repeating.
References Cited (Backward Citations)
No citation records indexed.
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