AC Signal Stability via Digital Feedback Control
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Solution Overview
Problem
Automatic test equipment struggles to generate highly accurate and stable analog signals, especially in the presence of environmental fluctuations such as temperature changes, leading to time-consuming and disruptive calibration procedures, which can result in inaccurate testing and unnecessary device rejection or degradation.
Innovation Solution
A test system with an AC generating circuit and a digital controller that uses a peak detector and feedback loop to monitor and compensate for environmental variations in real-time, adjusting the AC signal characteristics to maintain accuracy within a few milliVolts, reducing the need for frequent calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analog signal generation is used without real-time compensation, then the system is simpler and requires less processing, but the signal accuracy deteriorates under environmental fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where the actual DC value representing the AC signal characteristic is continuously monitored and compared with a target DC value. The difference (error signal) is fed back to adjust the DC offset applied to the AC generating circuit, creating a closed-loop control system that automatically compensates for environmental variations and maintains signal accuracy.
Solution Approach 2:
The patent replaces manual calibration procedures with an automated digital control system. The digital controller automatically adjusts the DC offset based on real-time monitoring of the AC signal characteristics, eliminating the need for time-consuming manual calibration and reducing human intervention while maintaining or improving signal accuracy.
2Measurement precision
If frequent calibration procedures are implemented to maintain signal accuracy, then signal accuracy is improved, but test time increases and productivity decreases
Solution Approach 1:
The patent implements continuous monitoring and compensation of the AC signal characteristics throughout the testing process. Rather than performing discrete calibration steps at intervals, the system continuously adjusts the DC offset based on real-time feedback, ensuring signal accuracy is maintained without interrupting the test flow and maximizing productivity.
Solution Approach 2:
The system performs self-calibration by automatically detecting deviations in AC signal characteristics and correcting them through adjusted DC offset application. The test equipment calibrates itself without external intervention or manual adjustment, eliminating time-consuming calibration procedures while maintaining signal accuracy.
3Measurement precision
If manual calibration procedures are used to adjust for environmental variations, then signal accuracy can be improved, but the calibration process is time-consuming and disruptive to testing
Solution Approach 1:
The patent replaces manual calibration operations with an automated digital control system that continuously monitors AC signal characteristics and adjusts DC offset parameters. This automation eliminates the need for operators to perform time-consuming manual calibration procedures while maintaining or improving signal accuracy.
Solution Approach 2:
The system establishes the target DC value and compensation parameters in advance based on expected environmental conditions and signal requirements. This preliminary configuration allows the automated system to quickly respond to environmental variations without requiring time-consuming calibration procedures during testing.
4Adaptability or versatility
If multiple instruments are used to generate both digital and analog signals, then signal generation capability is improved, but device complexity and coordination requirements increase
Solution Approach 1:
The patent combines the digital control functions and analog signal generation functions into an integrated system. The digital controller that manages test sequencing and coordination also directly controls the DC offset applied to the AC generating circuit, eliminating the need for separate manual calibration instruments and reducing the number of independent components that require coordination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves stable and accurate AC signal generation, reducing test times and minimizing device rejection or degradation by providing near-real-time monitoring and compensation for environmental changes, maintaining signal stability and accuracy even under temperature fluctuations.
Implementation Method 1
generating a DC value representing a characteristic of an AC analog signal output from the AC generating circuit
Implementation Method 2
selectively providing an offset to the DC value based on a difference between the DC value and the DC target value; and applying the DC value with the offset to the AC generating circuit so as to control the characteristic of the generated AC analog signal
Data Source
AI summary
Automatic test equipment with multiple components to generate highly accurate and stable analog test signals and method for operating the test system in semiconductor manufacturing process are disclosed. Output analog signals from existing test systems often fail the stability and accuracy requirement with less than 10 mV variations for testing certain electronic devices, due in part to environmental condition variations such as temperature fluctuations. Traditional compensation mechanisms for temperature variations involve time consuming and disruptive calibration procedures. Disclosed here is a system and method that provides near real-time monitoring and compensation for temperature-induced variations via a digital control mechanism that compensates for environmental variations in a time scale of less than 10 milliseconds and maintains the AC output analog signal with 10 milliVolt accuracy.