Variable-Step ZQ Calibration Circuit for Memory Interface Impedance
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Solution Overview
Problem
Current ZQ calibration methods for semiconductor memories are inflexible and cannot be effectively adapted to different calibration scenarios, leading to challenges in achieving high-speed data transmission due to impedance mismatch.
Innovation Solution
A ZQ calibration circuit that includes a logic control circuit and a calibration circuit, capable of adjusting calibration step sizes to convert an initial calibration code into a target calibration code of a specific adjustment step size, allowing for flexible calibration in various scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed calibration step size is used in ZQ calibration, then the calibration process is simple, but it cannot adapt to different calibration scenarios and cannot simultaneously achieve short calibration time and high precision
Solution Approach 1:
The calibration step size is made dynamically adjustable through a step size selection circuit that can switch between different step sizes (first step size and second step size) based on calibration requirements. This dynamic adjustment capability allows the system to adapt to different calibration scenarios without requiring multiple fixed circuits, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The invention changes the calibration parameter (step size) from a fixed value to a variable that can be selected between at least two different values. The step size selection circuit enables switching between a first calibration step size and a second calibration step size, allowing the system to optimize calibration time or precision by selecting appropriate step sizes for different scenarios.
2Loss of time
If a large calibration step size is used, then the calibration time is shortened, but the calibration precision is reduced
Solution Approach 1:
The system dynamically selects calibration step size based on requirements: using a larger first step size when calibration time is critical, or a smaller second step size when calibration precision is prioritized. This dynamic selection resolves the contradiction by allowing the system to adapt the step size to the specific calibration scenario.
Solution Approach 2:
The invention applies different levels of calibration granularity (partial action) by offering multiple step sizes. When fast calibration is needed, a coarser step size is used for quick initial calibration. When high precision is needed, a finer step size is used. This partial action approach allows the system to achieve adequate calibration performance without always performing the most time-consuming fine-grained calibration.
3Measurement precision
If a small calibration step size is used, then the calibration precision is increased, but the calibration time is extended
Solution Approach 1:
The system dynamically adjusts step size based on whether precision or speed is the priority. The step size selection circuit allows switching to a smaller second step size when high precision is required, while accepting the trade-off of longer calibration time. Conversely, it can switch to a larger first step size when time is more critical, resolving the contradiction between precision and time.
4Speed
If ZQ calibration is performed to ensure high-speed data transmission, then data transmission speed is improved, but impedance mismatch issues persist due to inflexible calibration methods
Solution Approach 1:
The invention changes the calibration parameter (step size) from fixed to variable, enabling the system to select appropriate calibration granularity for different scenarios. This allows more accurate impedance matching by selecting finer step sizes when needed, thereby improving both data transmission speed and reliability simultaneously.
Data Source
AI summary
Implementations of the present disclosure disclose a circuit for ZQ calibration. The circuit may include a logic control circuit. The logic control circuit may include a calibration code generation circuit configured to generate an initial calibration code in response to a calibration command. The logic control circuit may include a mapping conversion circuit configured to control the calibration code generation circuit to convert the initial calibration code to a target calibration code of a target adjustment step size in response to a code adjustment signal. The circuit may further include a calibration circuit configured to calibrate interface impedance of a target semiconductor device based on the target calibration code.