Multi-Interface ZQ Calibration Circuit for Single-Command Memory Tuning
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Solution Overview
Problem
Existing memory devices support only a ZQ calibration feature for a single interface, leading to increased command and time requirements when performing calibration across multiple interfaces, which hampers high-speed and high-power efficiency.
Innovation Solution
A ZQ calibration circuit that supports multiple interfaces by generating separate calibration codes based on different reference voltages for each interface mode, allowing simultaneous calibration across all modes with a single command and within a single unit of time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ZQ calibration is performed on multiple interfaces using separate commands, then calibration accuracy for each interface is maintained, but the total command count and calibration time increase linearly with the number of interfaces
Solution Approach 1:
The patent combines multiple interface calibrations into a single unified ZQ calibration operation. The ZQ calibration circuit performs calibration for multiple interfaces simultaneously by sharing common calibration resources and executing one consolidated calibration command that calibrates all interfaces within a single calibration time window, rather than requiring separate commands for each interface.
Solution Approach 2:
The ZQ calibration circuit is designed with multi-functionality to handle multiple interface modes. It can detect different interface modes (such as DDR4 and DDR5) and automatically perform appropriate calibration procedures for each mode within the same calibration operation, making the calibration system universal across different interface types without requiring mode-specific calibration commands.
2Reliability
If ZQ calibration is performed on multiple interfaces using separate commands, then each interface can be calibrated independently, but the command complexity and control logic increase
Solution Approach 1:
The patent merges the control logic for multiple interface calibrations into a single unified command structure. Instead of requiring separate commands for each interface, the system accepts one ZQ calibration command that internally manages calibration for all interfaces, thereby reducing command complexity while maintaining independent calibration capability through internal multiplexing.
Solution Approach 2:
The ZQ calibration circuit acts as an intermediary that receives a single calibration command and internally distributes calibration operations to multiple interfaces. This intermediary layer abstracts the complexity from the external controller, allowing simple command issuance while the intermediary handles the complex coordination of multiple interface calibrations independently.
3Measurement precision
If separate ZQ calibration commands are used for each interface mode, then calibration can be performed for each mode, but the overall calibration process exceeds single-unit time allocation
Solution Approach 1:
The patent merges mode-specific calibration operations into a single time-window calibration process. The ZQ calibration circuit detects the active interface mode and performs the appropriate calibration procedure within a single calibration time unit, combining what would otherwise require multiple sequential calibration operations into one concurrent process that maintains mode-specific precision.
Solution Approach 2:
The calibration system is designed to be dynamic, automatically adapting its calibration procedure based on the detected interface mode. When a mode change is detected (e.g., from DDR4 to DDR5), the ZQ calibration circuit dynamically adjusts its calibration parameters and procedures while operating within the same time unit, enabling mode-specific calibration without requiring separate time allocations for each mode.
Data Source
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AI summary
A ZQ calibration circuit (1000) includes: a ZQ controller (1100) configured to detect an end of one interface mode, among a plurality of interface modes in which ZQ calibration is supported, and to instruct a switch to another interface mode in response to the one interface mode coming to an end; a ZQ engine (1200) configured to generate a first reference voltage corresponding to the one interface mode through a multi-reference voltage generator (1210), to generate a second reference voltage corresponding to the another interface mode in response to the switch to the another interface mode being instructed, to perform the ZQ calibration based on the first reference voltage or the second reference voltage, and to output a calibration code; and a ZQ driver (1300) configured to output an output signal through an input/output pad based on the calibration code.