I/O Circuit Driving Impedance Calibration Using Segmented Basic Impedances
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Solution Overview
Problem
Existing I/O circuit calibration methods are inadequate in achieving high accuracy and resolution for driving impedance calibration, particularly in high-speed signal exchange applications, due to limitations in calibration resolution and the need for external precision resistors, which increase costs and resource usage.
Innovation Solution
A method and apparatus that utilize a built-in adjustable calibration impedance within a chip to calibrate driving impedance by selectively conducting basic impedances, allowing for precise estimation of driving impedance values through voltage division and comparison with reference voltages, thereby enhancing calibration resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external precision resistors are used for calibration, then calibration accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the calibration function from external components and implements it within the chip using built-in basic impedances. The calibration impedance is synthesized by selectively conducting multiple basic impedances inside the chip, eliminating the need for external precision resistors while maintaining calibration accuracy.
Solution Approach 2:
The chip performs self-calibration using its own built-in basic impedances as reference standards. The calibration process is autonomous, requiring no external calibration equipment, and the chip uses its internal resources to achieve accurate driving impedance calibration.
2Manufacturing precision
If calibration resolution is increased, then driving impedance accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The calibration impedance is segmented into multiple basic impedances that can be selectively conducted. By dividing the calibration function into discrete selectable units, the system achieves high calibration resolution through combination of basic units rather than requiring a single complex high-precision component.
Solution Approach 2:
The calibration impedance is made dynamically adjustable by selectively conducting different numbers of basic impedances. This dynamic configuration allows the calibration impedance to be adaptively tuned to match various driving impedance requirements, achieving high accuracy without fixed complex structure.
3Measurement precision
If more basic impedances are synthesized, then calibration resolution is improved, but area of the chip increases
Solution Approach 1:
Multiple basic impedances are merged in parallel or series configurations to synthesize the calibration impedance. By combining multiple smaller impedance units rather than using a single large impedance element, the system achieves high calibration resolution while optimizing chip area utilization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the calibration resolution and accuracy of driving impedance, reducing the need for external components and resources, and ensures compliance with signal interface standards for accurate signal exchange, especially in high-speed applications.
Implementation Method 1
voltage is divided between the first operating voltage and the second operating voltage to reflect a result from the voltage-dividing at the output end
Data Source
AI summary
An I/O calibration method and an apparatus are provided for calibrating a driving impedance at an output end of an I/O circuit in a chip. The chip further includes a plurality of basic impedances and a non-volatile memory. The I/O circuit calibration method includes: measuring an impedance value of one basic impedance and recording the measured impedance value in the non-volatile memory; synthesizing a calibration impedance by selectively conducting the basic impedance(s); adjusting the number of the conducted basic impedance(s) in the calibration impedance and estimating an impedance value of the driving impedance according to the measured result and a voltage divided by the calibration impedance and the driving impedance at the output end.