Delay Measurement Using Uncorrelated Signal Transition Averaging
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Solution Overview
Problem
High precision time measurement in circuits is hindered by manufacturing tolerances in delay elements, particularly at high speeds where traditional measurement techniques struggle with timing accuracy due to the short delays approaching or below the clock cycle length.
Innovation Solution
A delay measurement apparatus using a clock, digital signal source uncorrelated with the clock, detectors, accumulators, and a calculation device to calculate the average delay time by tracking transitions through the delay unit, providing accurate measurements by averaging multiple iterations and utilizing noise to reduce correlation with the clock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional clock cycle counting method is used to measure delay, then the measurement method is simple, but the measurement precision deteriorates when delay approaches or drops below clock cycle length
Solution Approach 1:
The patent segments the delay measurement into multiple discrete transition events. By counting individual transitions of the digital signal through the delay unit and correlating them with clock cycles, the measurement is broken down into measurable discrete units rather than attempting to measure the entire delay as a single continuous value.
Solution Approach 2:
The patent introduces an intermediary digital signal with uncorrelated transitions that acts as a probe through the delay unit. This intermediary signal allows indirect measurement of delay by observing the time relationship between input and output transitions relative to clock edges, rather than directly measuring the delay itself.
2Speed
If delay elements are reduced to minimum possible delay for high speed operation, then the circuit speed improves, but the manufacturing tolerance spread causes significant timing inaccuracies
Solution Approach 1:
The patent replaces physical mechanical adjustment of delay elements with a digital measurement and correction system. Instead of physically tuning delay elements to compensate for manufacturing variations, the system uses digital counting and calculation to measure actual delays and apply computational corrections.
Solution Approach 2:
The patent changes the measurement parameter from absolute delay time to relative transition counting. By measuring the number of clock cycles between correlated transitions and using statistical averaging, the system converts an absolute timing measurement problem into a relative counting problem that is less sensitive to manufacturing variations.
3Measurement precision
If multiple repeated measurements are averaged to improve precision, then the measurement accuracy improves, but the measurement time increases
Solution Approach 1:
The patent implements continuous measurement by continuously monitoring transitions of the digital signal through the delay unit. Rather than performing discrete separate measurements, the system continuously accumulates transition data and clock cycle counts, allowing measurements to be taken without interruption and averaged in real-time.
Data Source
AI summary
A delay measurement apparatus for measuring a delay unit comprising: a clock; clock counter; a digital signal source that is uncorrelated with the clock; a first detector arranged to detect transitions of the digital signal entering the delay unit; a first accumulator arranged to accumulate the current clock counter value based on the output of the first detector; a second detector arranged to detect transitions of the digital signal exiting the delay unit; a second accumulator arranged to accumulate the current clock counter value based on the output of the second detector; a measurement counter arranged to count the number of transitions of the digital signal passing through the delay unit; and a calculation device arranged to calculate an average number of clock cycles that elapse while a transition of the digital signal passes through the delay unit based on the first accumulator, the second accumulator and the measurement counter.