EP0098653A1
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EP
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High-stability clock signal regenerator
Assignee: Koninklijke Philips NV
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Filing: 1983-06-29
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Granted: —
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Expires: 2003-06-29
Abstract
Abstract A clock signal regenerator comprising a frequency control loop (1,2,3,4) which comprises a variable-frequency clock signal generator (2) is inter alia used in digital telephone exchanges, when a local clock signal must be generated from incoming clock signals (1-1, 1-N). The clock signal regenerator comprises a very stable auxiliary signal generator (9) and a first difference signal producer (11) for determining the frequency difference between the generated clock signal and the auxiliary signal. This frequency difference is determined periodically and written into a storage device (13). ln addition, the regenerator comprises a second difference signal producer (14) in which the difference is determined between a new frequency difference determined in the first difference signal producer (11) and the preceding frequency difference stored in the storage arrangement (13). Afther the incoming clock signals (1-1,...1-N) have dropped out the difference signal produced in the second difference signal producer (14) is applied as a control signal to the clock signal generator (2), the content of the storage device (13) not being changed. This has the advantage that the stability of the clock signal regenerator is then the same as the stability of the auxiliary signal generator.
Inventors
- 👤 Leendert Jan Hollaar
- 👤 Herman Zoetman
- 👤 Robert Jacques Marie Verbeek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 17:24
CPC Classifications
G; G06; G06F; G06F1/00; G06F1/04; G06F1/12; H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/14; H03L7/143; H04; H04L; H04L7/00; H04L7/0079; H04L7/0083
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
238 words
A clock signal regenerator comprising a clock signal generator whose frequency is controllable by a control signal, which clock signal generator is included in a control loop for synchronizing the frequency of the clock signal generated by the clock signal generator with an input signal applied to the control loop by means of a control signal derived from the frequency difference between the clock signal and the input signal, characterized in that the regenerator comprises an auxiliary signal generator for producing a fixed-frequency auxiliary signal, a first difference-signal producer connected to the auxiliary signal generator to which first difference signal producer at least the generated clock signal is applied in addition to the auxiliary signal to determine the frequency difference between the auxiliary signal and a signal which is proportional to the clock signal, a storage device connected to the first difference signal producer for storing the determined frequency difference, a second difference signal producer connected to the first difference signal producer and to the storage device to determine the difference between the frequency difference stored in the storage device and a signal produced by the first difference signal producer, which signal is proportional to the frequency difference between the auxiliary signal and the clock signal, and switching means for applying in the absence of a reliable input signal the signal produced by the second difference signal producer as a control signal to the controllable clock signal generator.
Claim 2
Dependent Claim
238 words
A clock signal regenerator comprising a clock signal generator whose frequency is controllable by a control signal, which clock signal generator is included in a control loop for synchronizing the frequency of the clock signal generated by the clock signal generator with an input signal applied to the control loop by means of a control signal derived from the frequency difference between the clock signal and the input signal, characterized in that the regenerator comprises an auxiliary signal generator for producing a fixed-frequency auxiliary signal, a first difference-signal producer connected to the auxiliary signal generator to which first difference signal producer at least the generated clock signal is applied in addition to the auxiliary signal to determine the frequency difference between the auxiliary signal and a signal which is proportional to the clock signal, a storage device connected to the first difference signal producer for storing the determined frequency difference, a second difference signal producer connected to the first difference signal producer and to the storage device to determine the difference between the frequency difference stored in the storage device and a signal produced by the first difference signal producer, which signal is proportional to the frequency difference between the auxiliary signal and the clock signal, and switching means for applying in the absence of a reliable input signal the signal produced by the second difference signal producer as a control signal to the controllable clock signal generator.
Claim 3
Dependent Claim
69 words
A clock signal regenerator as claimed in Claim 1, characterized in that the first difference signal producer comprises a first adding and subtracting arrangement to which the auxiliary signal and the generated clock signal are applied for increasing the counting position of the first adding and subtracting arrangement by means of one of the signals applied thereto and for decreasing the counting position by means of the adder signal.
Claim 4
Dependent Claim
40 words
A clock signal regenerator as claimed in Claim 2, characterized in that the switching means are arranged for applying to the storage arrangement the counting position of the first adder and subtracting arrangement when a reliable input signal is present.
Claim 5
Dependent Claim
72 words
A clock signal regenerator as claimed in Claim 3, characterized in that the input signal is also applied to the first difference signal producer and that the switching means are arranged for applying the input signal to the first adding and subtracting arrangement when a reliable input signal is present and for applying the generated clock signal to the first adder and subtracting arrangement in the absence of a reliable input signal.
Claim 6
Dependent Claim
112 words
A clock signal regenerator as claimed in Claim 2, characterized in that the input signal is also applied to the first difference signal producer and that the first difference signal producer comprises a second adding and subtracting arrangement to which the auxiliary signal and the input signal are applied for increasing the counting position of the second adding and subtracting arrangement by means of one of the signals applied thereto and for decreasing the counting position by means of the other signal and that the first switching means are arranged for applying the counting position of the second adding and subtracting arrangement to the store when a reliable input signal is present.
Claim 7
Dependent Claim
49 words
A clock signal regenerator as claimed in Claim 1, characterized in that the regenerator comprises a logic circuit to which several incoming clock pulse signals are applied and which is arranged for determining the control signal, the input signal being a weighted sum of the incoming clock pulse signals.
References Cited (Backward Citations)
DE2428495A1
Cited
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