Calibrating Multiple Temperature Sensors on Semiconductor Die
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Solution Overview
Problem
High-end integrated circuits face performance degradation and reliability issues due to temperature variations across the chip, which existing calibration methods struggle to accurately address, especially in production test environments with limited temperature control.
Innovation Solution
A system and method for calibrating multiple temperature sensing units using an interface to communicate with a device under test, generating calibration values based on logistic regression and sigmoid functions, and recalculating probabilities to ensure accurate temperature measurements across the chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple temperature sensing circuits are placed at several locations on the chip to obtain temperature information, then temperature measurement coverage is improved, but calibration complexity and time increase
Solution Approach 1:
The chip is divided into multiple temperature zones with separate temperature sensing circuits at each location. Each sensing circuit is calibrated independently using the probabilistic method, allowing parallel calibration processes that reduce total calibration time while maintaining comprehensive temperature coverage across the chip.
Solution Approach 2:
The calibration process uses probabilistic parameters (probability values and threshold values) to dynamically determine calibration acceptance. By changing from deterministic calibration criteria to probabilistic criteria, the system can quickly assess whether calibration values are acceptable without requiring exhaustive verification, significantly reducing calibration time.
2Measurement precision
If traditional calibration methods are used for temperature sensing circuits, then calibration process is simple, but calibration accuracy is insufficient under temperature variations
Solution Approach 1:
The calibration process incorporates feedback through probability value calculation and comparison with threshold values. The system calculates the probability that calibration values are accurate, compares this probability against a threshold, and uses this feedback to determine whether to accept or reject calibration values. This feedback mechanism ensures high calibration accuracy under temperature variations while maintaining a systematic calibration process.
Solution Approach 2:
The system performs preliminary calibration to generate initial calibration values, then uses probabilistic assessment to determine if these values are acceptable. If the probability value exceeds the threshold, the calibration is accepted without further action. This preliminary action approach avoids unnecessary recalibration steps while ensuring accuracy, balancing simplicity and precision.
3Productivity
If calibration values are generated without probabilistic verification, then calibration process is fast, but reliability of temperature measurements decreases
Solution Approach 1:
The system performs a probabilistic verification that is sufficient but not excessive. By calculating probability values and comparing them against threshold values, the system performs just enough verification to ensure reliability without requiring exhaustive testing. This partial verification approach maintains calibration speed while significantly improving reliability compared to no verification.
Solution Approach 2:
The system changes from deterministic calibration acceptance to probabilistic calibration acceptance. By using probability values and threshold values as parameters, the system can quickly assess calibration reliability without exhaustive verification. The probabilistic parameter approach enables the system to maintain high calibration speed while ensuring adequate reliability through statistical assessment.
Data Source
AI summary
A system is disclosed, including an interface to a DUT and a testing apparatus. The DUT includes a first plurality of temperature sensing circuits. The testing apparatus may store a plurality of control values. Each control value may depend on at least two calibration values of corresponding temperature sensing circuits of a second plurality of temperature sensing circuits. The testing apparatus may generate a plurality of calibration values for the DUT. Each calibration value corresponds to one of the first plurality of temperature sensing circuits. The testing apparatus may determine a plurality of test values for the DUT. The testing apparatus may calculate a probability value, and repeat generation of the plurality of calibration values upon determining that the probability value is less than a predetermined threshold value. The probability value corresponds to a likelihood that the plurality of calibration values is accurate.