On-Die I/O Buffer Impedance Calibration Without Precision Resistors
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Solution Overview
Problem
Current calibration methods for input/output (I/O) buffers in semiconductor dies require an on-board precision resistor, increasing implementation costs and limiting the functionality of dedicated I/O buffers due to process, temperature, and voltage variations.
Innovation Solution
Incorporating a temperature sensor and supply sensor on the semiconductor die to acquire and store temperature and voltage information, allowing the I/O buffer to self-calibrate its impedance without the need for an on-board precision resistor, enabling continuous calibration for process, temperature, and voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an on-board precision resistor is used for calibration, then impedance calibration accuracy is improved, but implementation cost increases
Solution Approach 1:
The patent extracts the calibration function from the traditional on-board precision resistor approach and implements it using existing on-die resources (temperature sensor, supply sensor, and I/O buffer itself). This eliminates the need for external calibration components while maintaining calibration accuracy through software-based compensation algorithms that account for temperature and voltage variations.
Solution Approach 2:
The I/O buffer performs self-calibration using its own integrated sensors (temperature sensor and supply sensor) and control logic. The buffer automatically adjusts its impedance characteristics by reading sensor data and applying compensation through its driver circuitry, eliminating the need for external calibration components and manual adjustment.
2Reliability
If a dedicated I/O buffer is used for calibration, then calibration functionality is improved, but the buffer's ability to perform other functions is limited
Solution Approach 1:
The patent makes the I/O buffer universal by enabling it to perform both calibration functions and normal data I/O functions. The same buffer can be configured for calibration when needed and then switched back to data transmission mode, eliminating the need for separate dedicated calibration buffers and maximizing resource utilization.
Solution Approach 2:
The I/O buffer's function is made dynamic and reconfigurable through software control. The buffer can switch between calibration mode and data I/O mode based on system requirements, with its impedance characteristics being adjusted dynamically according to temperature and voltage conditions detected by integrated sensors.
3Measurement precision
If traditional calibration methods are used, then impedance calibration is achieved, but continuous calibration for varying conditions is not possible
Solution Approach 1:
The patent implements a feedback mechanism where the I/O buffer continuously monitors temperature and voltage conditions through integrated sensors, compares current conditions against calibration data, and automatically adjusts its impedance characteristics in real-time. This closed-loop feedback system enables continuous adaptation to varying operating conditions without requiring external intervention.
Solution Approach 2:
The system performs preliminary calibration actions by storing impedance compensation data for various temperature and voltage conditions in memory during manufacturing or initial setup. When operational, the buffer quickly retrieves pre-computed compensation values based on current sensor readings, enabling rapid adaptation without requiring time-consuming real-time calculations or external calibration equipment.
Data Source
AI summary
A system for calibrating impedance of an input/output (I/O) buffer on a semiconductor die includes: the I/O buffer; a temperature sensor on the semiconductor die; and a supply sensor on the semiconductor die. The temperature sensor is configured to acquire temperature information for calibrating the I/O buffer. The supply sensor is configured to acquire voltage information for calibrating the I/O buffer. The I/O buffer comprises: a memory component coupled to the temperature and supply sensors and configured to store the acquired temperature or voltage information; a logic component coupled to the memory component; and a driver with driver legs. The driver is coupled to the logic component. The logic component is configured to generate driver control signals representing an on/off configuration for the driver legs of the driver based at least in part on the acquired temperature information or the acquired voltage information stored in the memory component.