RC Time Constant Measurement Using Automated Decay Detection
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Solution Overview
Problem
Current methods for determining the RC time constant of an electrostatic discharge (ESD) pulse are inaccurate and time-consuming due to manual cursor placement on oscilloscopes, leading to human error and loss of precision and accuracy.
Innovation Solution
Automated mechanisms for selecting fixed or user-inputted start times and iterating through sampled data points to identify corresponding x-axis values that satisfy specific y-axis relationships, using digital filtering and curve fitting to improve signal-to-noise ratio and accuracy of RC time constant measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual cursor placement on oscilloscope is used to measure RC time constant, then the measurement process is simple to perform, but the measurement precision and accuracy deteriorate due to human error and cursor resolution limitations
Solution Approach 1:
The patent replaces the manual mechanical cursor placement system with an automated computational system. The oscilloscope captures the ESD pulse waveform and stores it in memory, then a processor automatically analyzes the stored data to identify the RC time constant by finding the point where the decay curve reaches 36.8% of its initial value. This substitution eliminates human error in cursor placement and achieves higher measurement precision while maintaining ease of operation.
2Device complexity
If manual cursor manipulation is used to determine RC time constant, then the measurement process requires minimal equipment, but the productivity deteriorates due to time-consuming manual adjustment
Solution Approach 1:
The patent implements preliminary action by automatically capturing and storing the ESD pulse waveform in the oscilloscope memory before analysis. The system pre-processes the waveform data and automatically identifies the RC time constant point (36.8% decay level) without requiring manual cursor manipulation. This preliminary automated analysis significantly increases measurement productivity while keeping the equipment complexity minimal, as it uses standard oscilloscope capabilities.
3Measurement precision
If automated digital filtering and curve fitting is applied to ESD pulse analysis, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex manual signal processing with automated digital filtering and curve fitting algorithms executed by the oscilloscope processor. The system applies digital filters to remove noise from the captured ESD pulse waveform, then uses curve fitting to accurately model the exponential decay and precisely identify the RC time constant at the 36.8% decay point. This automated approach improves measurement precision while managing device complexity through software-based processing rather than additional hardware.
Data Source
AI summary
In general, the subject matter described in this disclosure can be embodied in methods, systems, and program products for characterizing a device under test. An electrical waveform is received from the device under test and sampled to generate an array of data values. User input selects a particular position of the electrical waveform on a display, and identifies a corresponding starting time. A decay of a value at the starting time is identified and the array is analyzed to identify multiple data values that correspond to the decayed value. An ending time is then determined using the multiple data values, and a decay time between the starting time and ending time is determined and presented on a display device.