Optimal Data Eye for Improved Vref Margin
AssigneeInvecas, Inc.
InventorsVenkata N.S.N. Rao, Ravindra Kantamani, Prasad Chalasani
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Abstract
An optimized method, system, and apparatus for determining optimal DQS delay for DDR memory interfaces are disclosed. The method performs data eye training in a two dimensional space with time delay value as x-axis and reference voltage (Vref) as y-axis to determine a rectangular data eye within an overall data eye with Vref margin.
Claims17
A system for data eye training comprising:
- a memory device having a data input and a data strobe input;
- and
- a training control interface having a data generation and comparison logic and state machines,
- wherein the training control interface is coupled to the data input and the data strobe input for writing data to and reading data from the memory device,
- wherein the state machines are operable by the data generation and comparison logic for determining a largest rectangular area within a data eye, and
- wherein the training control interface is operable to set a reference voltage and a data strobe timing to the middle of the largest rectangle area within the data eye.
A non-transitory computer readable medium having computer executable instructions stored thereon for aligning a data strobe signal to a data signal of a memory device, wherein the instructions include the steps comprising:
- determining points A, B, C, and D of the data signal that cross at a reference voltage and at a sum of the reference voltage and a reference voltage margin;
- determining a largest rectangle that fits within the determined points A, B, C, and D;
- comparing the determined largest rectangle with a previous best rectangle, wherein if the determined largest rectangle is greater in area than the previous best rectangle, then the determined largest rectangle is stored as the previous best rectangle;
- and
- setting a delay for the data strobe signal based on a center of the previous best rectangle.
Dependencies are inferred from the claim text.