Supporting Calibration For Sub-Rate Operation In Clocked Memory Systems

An apparatus to calibrate a clocked memory system, comprising:

• a calibration mechanism to perform a calibration operation at a first frequency to determine a first calibration state for a delay between a clock signal and a corresponding data signal in the clocked memory system;
• wherein the calibration mechanism is to use the first calibration state to determine a second calibration state, which is different than the first calibration state, for operation of the clocked memory system at a second frequency;
• and
• wherein the clocked memory system is to use the second calibration state when the clocked memory system is operating at the second frequency.

An apparatus to calibrate a clocked memory system, comprising:

• a calibration mechanism to perform a calibration operation at a first frequency to determine a first calibration state for a delay between a clock signal and a corresponding data signal in the clocked memory system;
• wherein
• the calibration mechanism is to use the first calibration state to determine a second calibration state, which is different than the first calibration state, for operation of the clocked memory system at a second frequency,
• the clocked memory system is to use the second calibration state when the clocked memory system is operating at the second frequency,
• the first calibration state includes a first pipeline delay component and a first offset component, and the second calibration state includes a second pipeline delay component and a second offset component, and
• the calibration mechanism is to identify the second calibration state from the first calibration state by one of
• (1) setting the second pipeline delay component to be equal to the first pipeline delay component and setting the second propagation delay component to be equal to the first propagation delay component divided by a ratio between the first frequency and the second frequency, or
• (2) setting the second propagation delay component to be equal to the first propagation delay component, and setting the second pipeline delay component to be equal to the first pipeline delay component multiplied by a ratio between the first frequency and the second frequency.

An apparatus to calibrate a clocked memory system, comprising:

• a calibration mechanism to perform a calibration operation at a first frequency to determine a first calibration state for a delay between a clock signal and a corresponding data signal in the clocked memory system;
• wherein
• the calibration mechanism is to use the first calibration state to determine a second calibration state, which is different than the first calibration state, for operation of the clocked memory system at a second frequency;
• the calibration mechanism is also to use the first calibration state to determine a third calibration state, which is different than each of the first calibration state and the second calibration state, for operation of the clocked memory system at a third frequency;
• the clocked memory system is to use the second calibration state when the clocked memory system is operating at the second frequency, and the clocked memory system is to use the third calibration state when the clocked memory system is operating at the third frequency;
• and
• the second and third frequencies are each less than the first frequency and are each respective fractions of the first frequency.