Uniquify, Incorporated

Uniquify IP Company, LLC

Venkat Iyer

Mahesh Gopalan

David Wu

Jung Gu Lee

Brett Murdock

Prashant Joshi

A method for operating a data interface circuit whereby calibration adjustments for data bit capture are made without disturbing normal system operation includes initially establishing, using a first calibration method where a data bit pattern received by the data interface circuit is predictable, an optimal sampling point for sampling data bits received by the data interface circuit, and during a normal system operation and without disturbing the normal system operation, performing a second calibration method where the data bit pattern received by the data interface circuit is unpredictable. The second calibration method determines an amount of a timing drift for received data bit edge transitions and adjusts the optimal timing point determined by the first calibration method to create a revised optimal timing point. The second calibration method samples fringe timing points associated with the transition edges of a data bit.

Continuous adaptive data capture optimization for interface circuits

A computer-implemented method includes an act of configuring hardware to cause at least a part of the hardware to operate as a double data rate (DDR) memory controller, and to produce a capture clock to time a read data path, where a timing of the capture clock is based on a first clock signal of a first clock, delay the first clock signal to produce a delayed first clock signal, adjust the delay such that at least one clock edge of the delayed first clock signal is placed nearer to at least one clock edge of at least one data strobe (DQS), or at least one signal dependent on a DQS timing, and produce a modified timing of the capture clock based on the delay of the first clock signal.

Double data rate (DDR) memory controller apparatus and method

In accordance with one embodiment, a computer-implemented method is provided, comprising the act of: configuring code or hardware to cause at least part of the hardware to operate as a double data rate (DDR) memory controller and to: produce a capture clock to time a read data path, where a timing of the capture clock is based on a first clock signal of a first clock, delay the first clock signal to produce a delayed first clock signal, adjust the delay such that at least one clock edge of the delayed first clock signal is placed nearer to at least one clock edge of: at least one data strobe (DQS), or at least one signal dependent on a DQS timing, and produce a modified timing of the capture clock based on the delay of the first clock signal.

A data interface circuit wherein calibration adjustments for data bit capture are made without disturbing normal system operation, is described. A plurality of DLL capture and delay circuits for sampling a trained optimal sampling point as well as leading and trailing sampling points are defined. A first stream of data bits is input to the data interface circuit and using a first calibration method, a first optimal sampling point for sampling the data bits input is established. A second stream of data bits is input to the data interface circuit during normal system operation. A second calibration method is performed that is different from the first, the second calibration method being performed whereby: at least one reference data path is established for sampling transition edges of the second stream of data bits input to the data interface during normal system operation.

In accordance with one embodiment, a computer-implemented method is provided, comprising: configuring code to cause at least part of hardware to operate as a double data rate (DDR) memory controller and to produce one or more capture clocks, where: a timing of at least one of the one or more capture clocks is based on a first clock signal of a first clock, the first clock signal is a core clock signal or a signal derived from at least the core clock signal, the at least one of the one or more capture clocks is used to time a read data path, the at least one of the one or more capture clocks is used to capture read data into a clock domain related to a second clock, the first clock and the second clock being related in timing such that at least one of: the second clock is derived from the first clock, or the first clock is derived from the second clock; and providing access to the code.

In accordance with one embodiment, an apparatus is provided, comprising: a double data rate (DDR) memory controller that, when in operation, causes the apparatus to: capture a data bit input signal in a first core domain register that is communicatively coupled to a second core domain register; clock the first core domain register utilizing a first clock; clock the second core domain register utilizing a second clock; maintain a difference in time between an active edge of the second clock and a next active edge of the first clock, such that the difference in time corresponds to a capture clock delay value; and set the capture clock delay value during a power-on initialization calibration operation.

In accordance with one embodiment, an apparatus is provided, comprising: a double data rate (DDR) memory controller that, when in operation, causes the apparatus to: generate a core clock; generate a capture clock; receive a data (DQ) signal that is driven by a DDR memory, or a signal derived from the DQ signal; clock a first core domain register, based, at least in part, on the capture clock; clock a second core domain register, based, at least in part, on the core clock; and set a delay of a core clock delay element, utilizing at least one of: the first core domain register, a signal derived from the first core domain register, the second core domain register, or a signal derived from the second core domain register; wherein the double data rate (DDR) memory controller is configured such that the delay of the core clock delay element is set during a power-on initialization calibration operation.

A method for calibrating capturing read data in a read data path for a DDR memory interface circuit is described. In one version, the method includes the steps of delaying a core clock signal by a capture clock delay value to produce a capture clock signal and determining the capture clock delay value. The capture clock signal is a delayed version of the core clock signal. The timing for the read data path with respect to data propagation is responsive to at least the capture clock signal. In another version, timing for data capture is responsive to a read data strobe or a signal derived therefrom, and a core clock signal or a signal derived therefrom.

Method for calibrating capturing read data in a read data path for a DDR memory interface circuit

A data interface circuit wherein calibration adjustments for data bit capture are made without disturbing normal system operation, is described. A plurality of DLL capture and delay circuits for sampling a trained optimal sampling point as well as leading and trailing sampling points are defined. A first stream of data bits is input to the data interface circuit and using a first calibration method and a first set of values is established. A second stream of data bits is input to the data interface circuit during normal system operation. A second calibration method is performed that is different from the first, establishing a second set of values. Several fringe timing points are sampled. A drift amount is compared with a drift correction threshold value and the first optimal sampling point is shifted in time by the drift amount to revise the first optimal sampling point.

Circuits and methods are described for a DDR memory controller where two different DQS gating modes are utilized. These gating modes together ensure that the DQS signal, driven by a DDR memory to the memory controller, is only available when read data is valid. Two types of gating logic are used: Initial DQS gating logic, and Functional DQS gating logic. The Initial gating logic has additional timing margin in the Initial DQS gating value to allow for the unknown round trip timing during initial bit levelling calibration. DQS functional gating is then optimized during further calibration to gate DQS precisely as latency and phase calibration are performed, resulting in a precise gating value for Functional DQS gating. Providing dual gating modes is especially useful when data capture is performed at half the DQS frequency in view of rising clock rates for DDR memories.

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Sunnyvale, CA, United States of America

Venkat Iyer