System and method for using a learning sequence to establish communications on a high-speed nonsynchronous interface in the absence of clock forwarding
First Claim
1. A memory system comprising:
- a reference clock generator operable to generate a reference clock signal;
a first memory module coupled to the reference clock generator, the first memory module operable to generate an internal clock signal based at least in part on the reference clock signal;
a second memory module coupled to the reference clock generator and operable to generate an internal clock signal based at least in part on the reference clock signal, the second memory module being coupled to the first memory module, the second memory module operable to transmit data to the first memory module and to receive data from the first memory module; and
wherein the first and second memory modules each comprises a receiver comprising;
a phase adjustment circuit configured to receive data and a predetermined pattern of data, and operable to compare the received data and the predetermined pattern of data to adjust a phase of its internal clock signal based on the comparison to generate a receive clock signal; and
a capture circuit coupled to receive the receive clock signal from the phase adjustment circuit and the data transmitted from the other memory module, the capture circuit being operable to capture the data transmitted from the other memory module in the receiver responsive to the receive clock signal.
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Abstract
A memory system includes a memory hub controller that sends write data to a plurality of memory modules through a downstream data bus and receives read data from the memory modules through an upstream data bus. The memory hub controller includes a receiver coupled to the upstream data bus and a transmitter coupled to the downstream data bus. Similarly, each of the memory modules includes a receiver coupled to the downstream data bus and a transmitter coupled to the upstream data bus. Each receiver includes a receive clock generator that is synchronized by coupling a known pattern of data to the receiver. The receiver determines which phase of the receive clock best captures the known pattern and uses that receive clock phase during normal operation.
601 Citations
29 Claims
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1. A memory system comprising:
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a reference clock generator operable to generate a reference clock signal; a first memory module coupled to the reference clock generator, the first memory module operable to generate an internal clock signal based at least in part on the reference clock signal; a second memory module coupled to the reference clock generator and operable to generate an internal clock signal based at least in part on the reference clock signal, the second memory module being coupled to the first memory module, the second memory module operable to transmit data to the first memory module and to receive data from the first memory module; and wherein the first and second memory modules each comprises a receiver comprising; a phase adjustment circuit configured to receive data and a predetermined pattern of data, and operable to compare the received data and the predetermined pattern of data to adjust a phase of its internal clock signal based on the comparison to generate a receive clock signal; and a capture circuit coupled to receive the receive clock signal from the phase adjustment circuit and the data transmitted from the other memory module, the capture circuit being operable to capture the data transmitted from the other memory module in the receiver responsive to the receive clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for managing asynchronous communication between a first and a second memory module, the method comprising:
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receiving a reference clock signal at the first memory module; generating a receive clock signal in the first memory module, the receive clock signal having a phase that is different from a phase of the reference clock signal; receiving a data pattern to match to a predetermined pattern of data; incrementally adjusting the phase of the receive clock signal based on the received data pattern matching the predetermined pattern of data; and utilizing the receive clock signal to strobe data into the first memory module. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A memory module configured to receive data and operable to generate an internal clock signal responsive to a received reference clock signal, the memory module comprising:
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a plurality of memory devices; and a receiver coupled to the memory devices, the receiver comprising; a phase adjustment circuit configured to receive the receive data and a predetermined pattern of data, and operable to compare the receive data to the predetermined pattern of data and adjust a phase of the internal clock signal based on the comparision to generate a receive clock signal; and a capture circuit coupled to receive the receive clock signal from the phase adjustment circuit and data transmitted to the memory module, the capture circuit being operable to capture data in the receiver responsive to the receive clock signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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Specification