DELAY LINE SYNCHRONIZER APPARATUS AND METHOD
First Claim
Patent Images
1. A method for generating a clock signal, comprising:
- receiving a first clock signal;
generating a second clock signal based on the first clock signal, the second clock signal having a higher clock frequency than the first clock signal and further having a phase relationship with respect to the first clock signal related to a first time delay and relative to a rising or falling edge of the first clock signal;
adjusting the first time delay to which the phase relationship between the first and second clock signals is related to a second time delay;
monitoring the phase relationship between the first and second clock signals during adjustment of the first time delay to the second time delay; and
generating a third clock signal based on the first clock signal, the third clock signal having the clock frequency of the second clock signal and having a phase relationship with respect to the first clock signal related to the second time delay relative to the rising or falling edge to which the first time delay was relative.
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Abstract
A synchronizer system and method that can be used with a conventional adjustable delay circuit to preserve a pseudo-synchronous phase relationship between clock signals of different clock domains when the time delay of the adjustable delay circuit from which one of the clock signals is output is changed.
118 Citations
55 Claims
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1. A method for generating a clock signal, comprising:
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receiving a first clock signal;
generating a second clock signal based on the first clock signal, the second clock signal having a higher clock frequency than the first clock signal and further having a phase relationship with respect to the first clock signal related to a first time delay and relative to a rising or falling edge of the first clock signal;
adjusting the first time delay to which the phase relationship between the first and second clock signals is related to a second time delay;
monitoring the phase relationship between the first and second clock signals during adjustment of the first time delay to the second time delay; and
generating a third clock signal based on the first clock signal, the third clock signal having the clock frequency of the second clock signal and having a phase relationship with respect to the first clock signal related to the second time delay relative to the rising or falling edge to which the first time delay was relative. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of generating a clock signal based on a first clock signal, the method comprising:
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generating an internal clock signal based on the first clock signal having a higher clock frequency than the first clock signal, the internal clock signal having an initial phase relationship relative to a clock edge of the first clock signal;
changing the initial phase relationship of the internal clock signal to the first clock signal to an adjusted phase relationship;
generating a phase synchronizer signal having a phase relationship relative to the first clock signal and a logic level to track the clock edge to which the initial phase relationship is relative; and
based on the phase synchronizer signal, generating the internal clock signal having the adjusted phase relationship and further having a first clock pulse relative to the same clock edge from which the initial phase relationship was relative. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A clock synchronizer circuit for coupling to a delay circuit, the delay circuit having an input and output and further having a control terminal to which control signals are applied to set a time delay of the delay circuit, the clock synchronizer circuit comprising:
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a clock synchronizer input circuit having an input to which a clock synchronizer control signal is applied to initiate a clock synchronizer operation, a clock terminal to which a first clock signal is applied, and further having an output at which an initiate signal is provided in response to the first clock signal;
a first shift register having an input coupled to the output of the clock synchronizer input circuit, a clock terminal to which a second clock signal is applied, and further having an output providing an output signal in response to the second clock signal, the second clock signal having a higher clock frequency than the first clock signal;
a second shift register having an input coupled to the output of the first shift register, a clock terminal to which the second clock signal is applied, and further having an output providing an output signal in response to the second clock signal;
an input multiplexer control circuit having an input at which a trigger signal is provided, a clock terminal to which the second clock signal is applied, and further having an output at which an input multiplexer select signal is provided in response to the second clock signal, the input multiplexer select signal based on the trigger signal;
an input multiplexer having a first input to which the second clock signal is applied, a second input coupled to a reference voltage supply, an output terminal coupled to the input of the delay circuit, and further having a control terminal coupled to the output of the second multiplexer control circuit to couple the output terminal to the first or second inputs in response to the input multiplexer select signal; and
a clock phase tracking circuit having an input coupled to the output of the second shift register, a clock terminal to which the second clock signal is applied, and further having an output at which a trigger signal is provided, the clock phase tracking circuit operable to track a phase relationship of a last clock pulse of the internal clock signal relative to the first clock signal and, in response to the clock synchronizer control signal, further operable to output a trigger signal to cause the delay circuit to output a first clock pulse of the internal clock signal at a time relative to the first clock signal to maintain the tracked phase relationship. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A clock generator, comprising:
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a delay circuit having input and output terminals, and further having a control terminal at which control signals are applied to set a time delay of the delay circuit; and
a synchronizer circuit having a synchronizer input circuit having an input to which a initiation signal is applied, a clock terminal to which a first clock signal is applied, and an output at which the initiation signal is coupled in response to the first clock signal;
a shift register having an input terminal coupled to the output of the synchronizer input circuit, an output terminal, and a clock terminal to which a second clock signal is applied, the shift register shifting a logic level applied to the input terminal to the output terminal in response to the second clock signal, the shift register further having an upstream tap and a downstream tap at which the logic level propagating through the shift register is coupled at first and second times, respectively;
an input multiplexer having a first input to which the second clock signal is applied, a second input coupled to a reference voltage supply, an output coupled to the input of the delay circuit, and further having a selection terminal, the input multiplexer selectively coupling the first or second input to the output according to an input multiplexer control signal; and
an input multiplexer control circuit having an input coupled to the downstream tap, a clock terminal to which the second clock signal is applied, and further having an output coupled to the selection terminal of the input multiplexer, in response to a first logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal to couple the second input of the input multiplexer to its output and further operable to generate a phase synchronizer signal to track the phase relationship of the second clock signal relative to a rising or falling edge of the first clock signal, in response to a second logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal based on the synchronizer signal to couple the first input of the input multiplexer to its output at a time to provide an output clock signal having a phase relationship relative to the rising or falling edge of the first clock signal tracked by the input multiplexer control circuit. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. A memory device, comprising:
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an address bus;
a control bus;
a data bus;
an address decoder coupled to the address bus;
a read/write circuit coupled to the data bus;
a data driver circuit coupled to the data bus;
a control circuit coupled to the control bus;
a memory-cell array coupled to the address decoder, control circuit, and read/write circuit; and
a clock generator coupled to the data driver to provide an internal clock signal, the clock generator comprising;
a delay circuit having input and output terminals, and further having a control terminal at which control signals are applied to set a time delay of the delay circuit; and
a synchronizer circuit having a synchronizer input circuit having an input to which a initiation signal is applied, a clock terminal to which a first clock signal is applied, and an output at which the initiation signal is coupled in response to the first clock signal;
a shift register having an input terminal coupled to the output of the synchronizer input circuit, an output terminal, and a clock terminal to which a second clock signal is applied, the shift register shifting a logic level applied to the input terminal to the output terminal in response to the second clock signal, the shift register further having an upstream tap and a downstream tap at which the logic level propagating through the shift register is coupled at first and second times, respectively;
an input multiplexer having a first input to which the second clock signal is applied, a second input coupled to a reference voltage supply, an output coupled to the input of the delay circuit, and further having a selection terminal, the input multiplexer selectively coupling the first or second input to the output according to an input multiplexer control signal; and
an input multiplexer control circuit having an input coupled to the downstream tap, a clock terminal to which the second clock signal is applied, and further having an output coupled to the selection terminal of the input multiplexer, in response to a first logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal to couple the second input of the input multiplexer to its output and further operable to generate a phase synchronizer signal to track the phase relationship of the second clock signal relative to a rising or falling edge of the first clock signal, in response to a second logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal based on the synchronizer signal to couple the first input of the input multiplexer to its output at a time to provide an output clock signal having a phase relationship relative to the rising or falling edge of the first clock signal tracked by the input multiplexer control circuit. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39)
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40. A processor-based system, comprising:
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a processor having a processor bus;
a system controller coupled to the processor bus, the system controller having a peripheral device port, the system controller further comprising a controller coupled to a system memory port;
at least one input device coupled to the peripheral device port of the system controller;
at least one output device coupled to the peripheral device port of the system controller;
at least one data storage device coupled to the peripheral device port of the system controller;
a memory bus coupled to the system controller for transmitting memory requests and responses thereon; and
a plurality of memory modules coupled to the memory bus, each of the modules having a plurality of memory devices and a memory hub coupled to the memory devices through a memory device bus to access the memory devices, the memory hub comprising;
a clock generator coupled to the data driver to provide an internal clock signal, the clock generator comprising;
a delay circuit having input and output terminals, and further having a control terminal at which control signals are applied to set a time delay of the delay circuit; and
a synchronizer circuit having a synchronizer input circuit having an input to which a initiation signal is applied, a clock terminal to which a first clock signal is applied, and an output at which the initiation signal is coupled in response to the first clock signal;
a shift register having an input terminal coupled to the output of the synchronizer input circuit, an output terminal, and a clock terminal to which a second clock signal is applied, the shift register shifting a logic level applied to the input terminal to the output terminal in response to the second clock signal, the shift register further having an upstream tap and a downstream tap at which the logic level propagating through the shift register is coupled at first and second times, respectively;
an input multiplexer having a first input to which the second clock signal is applied, a second input coupled to a reference voltage supply, an output coupled to the input of the delay circuit, and further having a selection terminal, the input multiplexer selectively coupling the first or second input to the output according to an input multiplexer control signal; and
an input multiplexer control circuit having an input coupled to the downstream tap, a clock terminal to which the second clock signal is applied, and further having an output coupled to the selection terminal of the input multiplexer, in response to a first logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal to couple the second input of the input multiplexer to its output and further operable to generate a phase synchronizer signal to track the phase relationship of the second clock signal relative to a rising or falling edge of the first clock signal, in response to a second logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal based on the synchronizer signal to couple the first input of the input multiplexer to its output at a time to provide an output clock signal having a phase relationship relative to the rising or falling edge of the first clock signal tracked by the input multiplexer control circuit. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47)
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48. A memory hub, comprising:
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a memory bus interface through which memory requests are received and memory responses are provided by the memory hub;
a local memory bus interface coupled to the memory bus interface through which memory device command, address and data signals are coupled, each signal having a timing relationship to at least one other signal;
a delay circuit coupled to the local memory bus interface to alter the timing relationship of at least one signal, the delay circuit having input and output terminals, and further having a control terminal at which control signals are applied to set a time delay of the delay circuit; and
a synchronizer circuit comprising;
a synchronizer input circuit having an input to which a initiation signal is applied, a clock terminal to which a first clock signal is applied, and an output at which the initiation signal is coupled in response to the first clock signal;
a shift register having an input terminal coupled to the output of the synchronizer input circuit, an output terminal, and a clock terminal to which a second clock signal is applied, the shift register shifting a logic level applied to the input terminal to the output terminal in response to the second clock signal, the shift register further having an upstream tap and a downstream tap at which the logic level propagating through the shift register is coupled at first and second times, respectively;
an input multiplexer having a first input to which the second clock signal is applied, a second input coupled to a reference voltage supply, an output coupled to the input of the delay circuit, and further having a selection terminal, the input multiplexer selectively coupling the first or second input to the output according to an input multiplexer control signal; and
an input multiplexer control circuit having an input coupled to the downstream tap, a clock terminal to which the second clock signal is applied, and further having an output coupled to the selection terminal of the input multiplexer, in response to a first logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal to couple the second input of the input multiplexer to its output and further operable to generate a phase synchronizer signal to track the phase relationship of the second clock signal relative to a rising or falling edge of the first clock signal, in response to a second logic level coupled to the downstream tap, the input multiplexer control circuit operable to generate an input multiplexer control signal based on the synchronizer signal to couple the first input of the input multiplexer to its output at a time to provide an output clock signal having a phase relationship relative to the rising or falling edge of the first clock signal tracked by the input multiplexer control circuit. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55)
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Specification