Memory Device Internal ZQ Calibration Manager
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Solution Overview
Problem
Existing semiconductor memory devices require external control for ZQ calibration, which acts as overhead for the memory controller or SoC, reducing efficiency and reliability.
Innovation Solution
A memory device with an internal ZQ manager that can initiate ZQ calibration independently, allowing for both external and internal ZQ modes, thereby distributing the control of ZQ calibration between the memory device and the memory controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ZQ calibration is controlled externally by memory controller or SoC, then calibration can be performed with external oversight, but it acts as overhead for the memory controller or SoC, reducing efficiency
Solution Approach 1:
The memory device performs ZQ calibration autonomously using an internal ZQ manager that generates calibration codes without requiring continuous external control from the memory controller or SoC. The device self-manages the calibration process, reducing overhead on external controllers while maintaining calibration reliability through internal execution.
2Ease of operation
If ZQ calibration is performed externally, then control can be centralized, but the maintenance operations act as overhead for the memory controller or SoC
Solution Approach 1:
The memory device autonomously performs ZQ calibration maintenance operations through its internal ZQ manager, eliminating the need for the memory controller or SoC to manage these operations. This self-service approach reduces controller overhead time while maintaining ease of operation through automated internal control.
Solution Approach 2:
The calibration control function is segmented between external initialization (memory controller sets ZQ mode) and internal execution (memory device performs calibration). This segmentation allows centralized control setup while distributing the time-consuming calibration execution to the memory device, reducing controller overhead.
3Extent of automation
If internal ZQ manager is added to memory device, then autonomous calibration is enabled, but device complexity increases
Solution Approach 1:
An internal ZQ manager is integrated into the memory device to enable autonomous ZQ calibration execution. This self-service capability allows the device to perform calibration independently without external intervention, achieving high automation. The complexity increase is minimal as the ZQ manager reuses existing internal resources like code generators and drivers already present in the memory device architecture.
Data Source
AI summary
A memory device includes a driver that drives a data line connected with an external device, an internal ZQ manager that generates an internal ZQ start signal, a selector that selects one of the internal ZQ start signal and a ZQ start command from the external device, based on a ZQ mode, a ZQ calibration engine that generates a ZQ code by performing ZQ calibration in response to a selection result of the selector, and a ZQ code register that loads the ZQ code onto the driver in response to a ZQ calibration command from the external device.