Test Circuit for Precision Delta Delay Measurement
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Solution Overview
Problem
Integrated circuits face challenges in accurately measuring signal delay as a function of stress on components, which is crucial for assessing the performance and reliability of signal paths.
Innovation Solution
A test circuit comprising an oscillator, a reference gate chain, a test gate chain, and a counter is used to measure the difference in propagation delay between the test and reference chains, with calibration and starter divider circuits to facilitate frequency measurement and adjust stress levels, enabling precise estimation of gate delay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional delay measurement methods are used, then measurement capability is provided, but measurement precision is insufficient for accurate stress analysis
Solution Approach 1:
The patent introduces an oscillator as an intermediary element that generates clock signals to measure propagation delay. The oscillator cycles serve as a reference medium to quantify the time difference between reference and test signal paths, enabling precise delay measurement that directly correlates with stress-induced performance degradation
Solution Approach 2:
The patent replaces conventional mechanical or electronic delay measurement systems with a timing-based measurement approach using oscillator cycles. Instead of direct time measurement, the system counts the number of oscillator cycles required for signals to propagate through reference and test paths, substituting complex time measurement mechanics with simpler cycle counting
2Measurement precision
If high-frequency oscillators are used for precise measurement, then measurement resolution improves, but frequency measurement difficulty increases
Solution Approach 1:
The calibration divider circuit serves as an intermediary that bridges the high-frequency oscillator output and the external frequency measurement instrument. It divides the high-frequency oscillator signal to a lower, more easily measurable frequency while maintaining the ability to calculate the original oscillator frequency through the known division ratio
Solution Approach 2:
The system performs preliminary frequency division of the oscillator signal before external measurement, making the frequency easier to measure with standard instruments. The division ratio is predetermined and stored, allowing the actual high-frequency oscillator characteristics to be derived from the lower-frequency measurement
Data Source
AI summary
A test circuit for measuring a gate delay as a function of stress is disclosed. The test circuit includes an oscillator, a reference gate chain, a test gate chain, and a counter. The counter measures the difference in propagation delay between the test chain and the reference chain in calibrated oscillator cycles. Differences in test gate delay as a function of applied stress may be measured within the calibration accuracy of the oscillator frequency. The use of the reference gate chain allows a simpler unipolar counter.