Test Apparatus Replica Driver Voltage Divider
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Solution Overview
Problem
Existing test apparatuses face challenges in accurately detecting response signals from devices under test (DUTs) due to superimposition of test signals, especially when generating test signals at short intervals, and struggle to account for varying output resistances among different DUTs, leading to inaccurate judgment of logic levels.
Innovation Solution
A test apparatus with a test signal generating section, main driving section, replica driving section, resistance voltage dividing section, comparing section, and adjusting section, which adjusts the voltage dividing ratio to ensure accurate comparison of response signals with threshold voltages, even when signals are superimposed and output resistances vary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If test signals are generated at shorter intervals to reduce overall test time, then productivity is improved, but measurement precision deteriorates because the response signal is superimposed by the next test signal
Solution Approach 1:
The patent uses a replica driver to create a copy of the driver's output voltage and a voltage divider circuit to generate a reference voltage that replicates the superimposed signal condition. This reference voltage is then used by the comparator to accurately detect the response signal even when superimposed by the next test signal, enabling high-speed testing without sacrificing measurement precision
Solution Approach 2:
The patent introduces a comparator as an intermediary element that compares the response signal with a reference voltage. This comparator acts as a mediator that can accurately determine the logic level of the response signal even in the presence of superimposed test signals, thereby maintaining measurement precision at high test speeds
2Device complexity
If a fixed voltage divider circuit is used to cancel driver output voltage, then device complexity is reduced, but measurement precision deteriorates because it cannot accurately cancel the output voltage for DUTs with varying output resistance
Solution Approach 1:
The patent employs an adjustable voltage divider circuit where the division ratio can be dynamically changed based on the DUT's output resistance characteristics. This dynamic adjustment capability allows the reference voltage to accurately match the superimposed signal condition for different DUTs, maintaining measurement precision without requiring complex circuit structures
Solution Approach 2:
The patent changes the resistance parameters of the voltage divider circuit to adapt to different DUT output resistance values. By adjusting the resistance values in the voltage divider, the reference voltage can be precisely tuned to cancel the driver output voltage for each specific DUT, achieving accurate measurement while keeping the circuit structure relatively simple
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
Enables accurate detection of logic levels and judgment of DUT acceptability, even at short test signal intervals and across DUTs with different output resistances, by effectively canceling driver output voltage and adjusting for varying resistance specifications.
Implementation Method 1
a resistance voltage dividing section that generates a divided voltage by resistance-dividing the comparison voltage
Data Source
AI summary
A test apparatus for testing a device under test includes a test signal generating section that generates a test signal to be supplied to the device under test, a main driving section that outputs an output voltage determined in accordance with the test signal, to an input/output pin connected to a signal input/output terminal of the device under test, a replica driving section that outputs a comparison voltage determined in accordance with the test signal, a resistance voltage dividing section that generates a divided voltage by resistance-dividing the comparison voltage, a comparing section that compares a voltage of the input/output pin with the divided voltage, a judging section that judges acceptability of the device under test based on a result of the comparison by the comparing section, and an adjusting section that adjusts a voltage dividing ratio of the resistance voltage dividing section so that the divided voltage becomes equal to a voltage obtained by adding together a predetermined threshold voltage and a voltage of the input/output pin that is observed when the main driving section has output the output voltage and the signal input/output terminal of the device under test has not output a response signal.