Memory ZQ Calibration with Autonomous Timing for Faster Bus Operation
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Solution Overview
Problem
The high communication frequency between memory devices and controllers increases the likelihood of errors during data transmission, leading to inefficiencies in bus operations due to the time required for ZQ calibration and status checks.
Innovation Solution
Implementing a memory device with both first-type and second-type ZQ calibration methods, where the first-type is initiated by a memory controller command and the second-type is performed autonomously based on internal conditions, reducing the need for external control and shortening calibration times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ZQ calibration is performed based on memory controller command (first-type), then communication reliability is improved, but bus efficiency deteriorates due to communication suspension
Solution Approach 1:
The memory device performs ZQ calibration in advance based on internally managed counts before communication is needed. By predicting when calibration will be required and performing it proactively, the system ensures communication reliability is maintained while avoiding unnecessary suspension of bus operations when calibration has already been completed.
Solution Approach 2:
The memory device autonomously manages its own ZQ calibration process using internal counters and state machines, independent of memory controller commands. This self-service approach allows the device to perform calibration at optimal moments without requiring the controller to initiate each calibration cycle, thereby improving bus efficiency while maintaining reliability.
2Reliability
If ZQ calibration is performed frequently to ensure reliability, then communication reliability is improved, but time loss increases due to repeated calibration operations
Solution Approach 1:
The memory device performs ZQ calibration periodically based on internally managed counts rather than continuously or on every communication event. This periodic approach ensures reliability by performing calibration at regular intervals while minimizing time loss by avoiding excessive calibration operations.
Solution Approach 2:
The system dynamically adjusts calibration timing by changing the parameter of calibration trigger conditions. Instead of fixed periodic calibration or calibration on every command, the system uses internal counters that track communication patterns and trigger calibration only when appropriate, optimizing the balance between reliability and time efficiency.
3Ease of operation
If memory device waits for controller command before calibration, then ease of control is improved, but operating speed deteriorates due to idle waiting time
Solution Approach 1:
The memory device performs ZQ calibration in advance based on internal predictions of when calibration will be needed, rather than waiting for controller commands. This preliminary action eliminates idle waiting time and improves operating speed while the controller retains overall control through the ability to request calibration when needed.
Solution Approach 2:
The memory device autonomously determines when calibration is needed and performs it without waiting for controller commands. This self-service mechanism improves operating speed by eliminating idle waiting time while maintaining ease of control through the dual-mode architecture where the controller can still initiate calibration when required.
Data Source
AI summary
A memory device includes data pads that are connected to an external memory controller, a ZQ pad that is connected to an external resistor, data drivers and receivers that are connected to the data pads and output first data signals to the data pads or receive second data signals from the data pads, and a ZQ calibrator that is connected to the ZQ pad. The memory device performs ZQ calibration based on a voltage of the ZQ pad, generates ZQ codes as a result of the ZQ calibration, and provides the ZQ codes to the data drivers and receivers. The ZQ calibrator performs a first-type ZQ calibration in response to a command received from the external memory controller and performs a second-type ZQ calibration without the command being received from the external memory controller.