Fail-safe zero delay buffer with automatic internal reference
First Claim
1. An apparatus comprising:
- a first circuit comprising (i) a control circuit configured to generate a control signal in response to a first reference signal and a second reference signal and (ii) an oscillator configured to generate said second reference signal in response to said control signal and a timing signal, wherein said control signal is held when said first reference signal is lost; and
a second circuit configured to generate one or more output signals in response to said second reference signal and one of said one or more output signals, wherein said one or more output signals have a controlled delay with respect to said first reference signal and said timing signal is generated independently of said one or more output signals.
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Abstract
An apparatus comprising a first circuit and a second circuit. The first circuit may comprise a control circuit and an oscillator. The control circuit may be configured to generate a control signal in response to a first reference signal and a second reference signal. The oscillator may be configured to generate the second reference signal in response to the control signal and a timing signal. The control signal is generally held when the first reference signal is lost. The second circuit may be configured to generate one or more output signals in response to the second reference signal and one of the one or more output signals. The one or more output signals may have a controlled delay with respect to the first reference signal.
88 Citations
20 Claims
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1. An apparatus comprising:
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a first circuit comprising (i) a control circuit configured to generate a control signal in response to a first reference signal and a second reference signal and (ii) an oscillator configured to generate said second reference signal in response to said control signal and a timing signal, wherein said control signal is held when said first reference signal is lost; and a second circuit configured to generate one or more output signals in response to said second reference signal and one of said one or more output signals, wherein said one or more output signals have a controlled delay with respect to said first reference signal and said timing signal is generated independently of said one or more output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for generating one or more output signals comprising:
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means for generating a second reference signal in response to (i) a first reference signal and (ii) a crystal oscillator signal, wherein (a) a frequency and a phase of said second reference signal are (i) adjusted in response to said first reference signal and (ii) held when said first reference signal is lost and (b) said crystal oscillator signal is generated independently of said one or more output signals; and means for generating said one or more output signals in response to said second reference signal and one of said one or more output signals.
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16. A method of generating one or more output signals comprising the steps of:
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(A) generating a second reference signal in response to (i) a first reference signal and (ii) a crystal oscillator signal, wherein a frequency and a phase of said second reference signal are (i) adjusted in response to said first reference signal and (ii) held when said first reference signal is lost and said crystal oscillator signal is generated independently of said one or more output signals; and (B) generating said one or more output signals in response to said second reference signal and one of said one or more output signals. - View Dependent Claims (17, 18, 19)
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20. An apparatus comprising:
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a digitally controlled reference loop circuit configured to generate a reference signal in response to (i) an external timing signal and (ii) a crystal oscillator signal, wherein a frequency and a phase of said reference signal are (i) adjusted in response to said external timing signal and (ii) held when said external timing signal is lost; and a second circuit (i) configured to generate one or more output signals in response to said reference signal and one of said one or more output signals and (ii) comprising a divide-by-N circuit configured to divide said one of said one or more output signals, wherein said crystal oscillator signal is generated independently of said one or more output signals.
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Specification