Memory ODT Calibration Using PVT Look-Up Codes
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Solution Overview
Problem
The challenge of lengthy ZQ calibration operations in multi-chip semiconductor packages due to process, voltage, and temperature variations, which affects operating speed and signal integrity.
Innovation Solution
A method utilizing a temperature-to-code (T2C) converter and a look-up table to determine calibration codes based on temperature and voltage data, coupled with a comparator to adjust transistor states for impedance matching, thereby reducing calibration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ZQ calibration operation is performed on each memory chip in a multi-chip package, then impedance matching is improved, but calibration time increases significantly
Solution Approach 1:
The patent pre-calculates and stores calibration codes for various PVT conditions in a look-up table during the design phase. During operation, the system only needs to query the table based on current temperature and voltage, rather than performing time-consuming calibration operations. This preliminary preparation resolves the contradiction by making the calibration process extremely fast while maintaining accuracy.
Solution Approach 2:
The system anticipates PVT variations and pre-computes compensation codes for all expected conditions. By storing these pre-computed codes in the look-up table, the system cushions against future calibration needs, allowing instant retrieval rather than real-time computation. This resolves the time-quality contradiction.
2Measurement precision
If traditional calibration methods are used without look-up table, then calibration accuracy is maintained, but operating speed decreases due to lengthy calibration time
Solution Approach 1:
The look-up table is pre-populated with accurate calibration codes for various PVT conditions during design. This preliminary action preserves calibration accuracy while enabling fast retrieval during operation, thus resolving the contradiction between accuracy and speed.
Solution Approach 2:
Instead of performing complex calibration computations in real-time, the system creates a copy of all possible calibration results in the look-up table. The runtime system simply copies the appropriate pre-computed code from the table based on current conditions, maintaining accuracy while dramatically improving speed.
Data Source
AI summary
Provided is a memory device including a temperature to code (T2C) converter configured to obtain temperature data, to obtain specification voltage data, to determine a calibration code corresponding to the obtained temperature and specification voltage data, and configured to transmit information about the determined calibration code to a code generator, the code generator configured to transmit the generated calibration code to a pull-down/up set circuit, the pull-down/up set circuit configured to determine opening and closing of a plurality of transistors to correspond to the calibration code received from the code generator, and configured to form a pull-down/up impedance, and a comparator configured to compare a magnitude of a first input voltage and the impedance of an on-die termination (ODT) circuit with a magnitude of a second input voltage and configured to transmit a calibration code change signal to the code generator based on a result of the voltage comparison.