Runtime ZQ Calibration in NAND Storage for Signal Integrity
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Solution Overview
Problem
High-capacity non-volatile memory devices face signal integrity issues due to increased frequency of input/output signals and impedance mismatch, particularly in high-capacity semiconductor packages, which are exacerbated by changes in operating environment.
Innovation Solution
Implementing a ZQ calibration method that allows for impedance matching between the storage controller and non-volatile memory devices by performing ZQ calibration during busy status checks using the DQ pin, ensuring optimal signal integrity through runtime adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity non-volatile memory devices are used to increase storage capacity, then storage capacity is improved, but signal integrity deteriorates due to impedance mismatch and increased I/O signal frequency
Solution Approach 1:
The patent implements dynamic ZQ calibration that adjusts impedance matching parameters in real-time based on operating conditions. The calibration is performed at multiple stages (initialization, runtime, and before/after operations) to adapt to changing environmental factors such as temperature and voltage, thereby maintaining signal integrity despite the high-capacity device's inherent impedance challenges
Solution Approach 2:
The patent changes electrical parameters (impedance matching values) through ZQ calibration to optimize signal transmission. By adjusting calibration values based on runtime conditions and operational status, the system compensates for impedance mismatch in high-capacity devices, resolving the contradiction between increased capacity and degraded signal integrity
2Measurement precision
If ZQ calibration is performed separately from operation commands, then calibration accuracy is improved, but system productivity deteriorates due to increased operation time
Solution Approach 1:
The patent merges ZQ calibration operations with normal memory access operations by performing calibration during the memory device's busy status. The calibration commands are interleaved with read/write operations, allowing impedance matching to be performed without dedicating separate time slots, thus maintaining both accuracy and productivity
Solution Approach 2:
The patent enables continuous operation by performing ZQ calibration during the memory device's busy period without halting normal operations. The calibration process runs concurrently with data transfers and other memory operations, ensuring that the useful action of data processing continues uninterrupted while calibration is performed
3Reliability
If impedance matching is optimized for specific operating conditions, then signal integrity is improved, but system adaptability deteriorates when operating environment changes
Solution Approach 1:
The patent implements dynamic recalibration that continuously adapts impedance matching parameters to changing environmental conditions. By monitoring runtime status and performing periodic ZQ calibration, the system automatically adjusts to temperature variations, voltage changes, and other environmental factors, maintaining signal integrity across diverse operating conditions
Solution Approach 2:
The system performs self-calibration by automatically detecting when calibration is needed and executing ZQ calibration routines without external intervention. The memory controller monitors operation status and triggers calibration during appropriate windows, enabling the system to self-adjust to environmental changes and maintain optimal signal integrity autonomously
Data Source
AI summary
An operating method of a storage system includes transmitting a first access command to a first non-volatile memory device, checking a status of the first non-volatile memory device, and performing a first ZQ calibration on the first non-volatile memory device through a DQ pin of the first non-volatile memory device during a time when the first non-volatile memory device is in a busy status.