Uniquify, Incorporated

Mahesh Goplan

Jung Gu Lee

A method for calibrating a read data path for a DDR memory interface circuit from time to time in conjunction with functional operation of a memory circuit is described. The method uses the steps of issuing a sequence of read commands so that a delayed dqs signal toggles continuously. Next, delaying a core clock signal originating within the DDR memory interface circuit to produce a capture clock signal. The capture clock signal is delayed from the core clock by a capture clock delay value. Next, determining an optimum capture clock delay value. The output of the read data path is clocked by the core clock. The timing for the read data path with respect to data propagation is responsive to at least the capture clock.

Methods for calibrating a read data path for a memory interface

A calibrating memory interface circuit is described wherein prior to a calibration operation at least a portion of application information contained in a memory circuit is moved or copied to an alternate location to preserve that information. At the completion of the calibration operation, the information is restored to the same location of the memory circuit. Thus, the calibration operation can be performed from time to time during normal operation of a system containing the memory circuit. Non-limiting examples of calibration operations are described including operations where a capture clock for a memory read circuit is calibrated, and operations where CAS latency compensation is calibrated for a DDR memory interface.

Application memory preservation for dynamic calibration of memory interfaces

A method for calibrating a memory interface circuit is described wherein prior to a calibration operation at least a portion of application information contained in a memory circuit is moved or copied to an alternate location to preserve that information. At the completion of the calibration operation, the information is restored to the same location of the memory circuit. Thus, the calibration operation can be performed from time to time during normal operation of a system containing the memory circuit. Non-limiting examples of calibration operations are described including operations where a capture clock for a memory read circuit is calibrated, and operations where CAS latency compensation is calibrated for a DDR memory interface.

Method of application memory preservation for dynamic calibration of memory interfaces

A method for quickly calibrating a memory interface circuit from time to time in conjunction with operation of a functional circuit is described. The method uses controlling the memory interface circuit with respect to read data capture for byte lanes, including controlling CAS latency compensation for the byte lanes. In the method control settings for controlling CAS latency compensation are determined and set according to a dynamic calibration procedure performed from time to time in conjunction with functional operation of a circuit system containing one or more memory devices connected to the memory interface circuit. In the method, determining and setting the control settings for controlling CAS latency compensation is performed independently and parallely in each of the byte lanes.

Methods for operating a memory interface circuit including calibration for CAS latency compensation in a plurality of byte lanes

A memory interface circuit for read operations is described. The circuit includes one or more controller circuits, one or more read data delay circuits for providing CAS latency compensation for byte lanes. In the system, control settings for the read data delay circuits for providing CAS latency compensation are determined and set using controller circuits according to a dynamic calibration procedure performed from time to time. In the system, determining and setting the control settings for the read data delay circuits for providing CAS latency compensation is performed independently and parallely in each of a plurality of byte lanes.

Memory interface circuits including calibration for CAS latency compensation in a plurality of byte lanes

A method for calibrating a DDR memory controller is described. The method provides an optimum delay for a core clock delay element to produce an optimum capture clock signal. The method issues a sequence of read commands so that a delayed version of a dqs signal toggles continuously. The method delays a core clock signal to sample the delayed dqs signal at different delay increments until a 1 to 0 transition is detected on the delayed dqs signal. This core clock delay is recorded as 'A.' The method delays the core clock signal to sample the core clock signal at different delay increments until a 0 to 1 transition is detected on the core clock signal. This core clock delay is recorded as 'B.' The optimum delay value is computed from the A and B delay values.

Dynamically calibrated DDR memory controller

A DDR memory controller is described wherein a core domain capture clock is created by programmably delaying the core clock of the memory controller. The delay of this capture clock is typically calibrated during a power on the initialization sequence in concert with a DDR memory in a system environment, thereby minimizing the effects of system delays and increasing both device and system yield. An additional embodiment also includes programmably delaying the incoming dqs signal. To compensate for voltage and temperature variations over time during normal operation, a runtime dynamic calibration mechanism and procedure is also provided.

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Santa Clara, CA, United States of America

Mahesh Goplan