Apple Inc.

David A Knopf

Robert E Jeter

Kai Lun Hsiung

Venkata Ramana Malladi

Jingkui Zheng

Rahul Ranjan

Satish B Dulam

An apparatus for performing a write data strobe concurrent with a reference voltage calibration is disclosed. A memory controller circuit is configured to convey a write clock signal to a memory. The memory controller circuit includes a calibration circuit configured to send a first command to memory to initiate a calibration of the write clock signal and, after an amount of time has elapsed, receive a calibration value from the memory. The memory controller further includes a delay circuit configured to apply a delay to the write clock signal, wherein the calibration circuit is configured to complete calibration of the write clock signal by adjusting the delay applied to the write clock signal in accordance with the calibration value. The calibration circuit is further configured to perform a reference voltage calibration concurrent with the calibration of the write clock signal.

Concurrent write data strobe and reference voltage calibrations

The present disclosure is directed to a reference voltage calibration. An apparatus includes a memory and a memory controller including a calibration circuit configured to perform a reference voltage calibration to determine a reference voltage used to distinguish between logic values read from the memory. The reference voltage calibration comprises performing horizontal calibrations at different reference voltage values to determine a range of delay values applied to a data strobe signal at which valid data is read from the memory. The calibration includes determining scores corresponding to ones of the plurality of horizontal calibrations in which a score for a particular one of the plurality of horizontal calibrations is based on a corresponding range of delay values and a reference voltage margin. Thereafter, the calibration circuit selects a calibrated reference voltage based on the scores corresponding to ones of the plurality of horizontal calibrations.

Nominal distance reference voltage calibration

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San Jose, CA, United States of America

David A Knopf