DAC Test Circuit Using Analog Difference Signals
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Solution Overview
Problem
The high manufacturing cost and complexity of test apparatuses with high-resolution analogue-to-digital converters (AD converters) make it difficult to test devices with high-resolution digital-to-analogue converters, as they require AD converters with matching or higher resolution, leading to increased manufacturing costs.
Innovation Solution
A test apparatus that uses a low-resolution AD converter to test devices with high-resolution digital-to-analogue converters by supplying a digital input signal, generating an analogue reference signal, calculating an analogue difference signal, and determining defects based on this signal, allowing for effective testing without the need for a high-resolution AD converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution AD converter is used in the test apparatus to test devices with high-resolution DA converters, then the measurement precision is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The test apparatus segments the measurement function into two parts: a low-resolution AD converter for basic digitization and a separate processing system (including a DA converter and signal processing unit) for achieving high-resolution measurement. This segmentation allows the use of simpler, lower-cost components while maintaining high measurement precision through computational methods.
Solution Approach 2:
The patent introduces an intermediary processing system that includes a DA converter and signal processing unit. This intermediary system bridges the gap between the low-resolution AD converter and the requirement for high-resolution measurement, enabling precise defect detection without requiring a high-resolution AD converter directly.
2Measurement precision
If a high-resolution AD converter is used in the test apparatus, then the measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs a low-resolution AD converter, which is cheaper and simpler to manufacture, combined with software-based processing to achieve the required measurement precision. This approach replaces the expensive high-resolution AD converter with a combination of cheaper hardware and processing algorithms.
Solution Approach 2:
The patent changes the operational parameters of the test system by using a low-resolution AD converter with additional processing steps rather than a high-resolution converter. This parameter change in the measurement approach allows cost reduction while maintaining precision through computational enhancement of the measurement process.
3Ease of manufacture
If a low-resolution AD converter is used to test high-resolution DA converters, then the manufacturing cost and complexity are reduced, but the measurement precision may be insufficient
Solution Approach 1:
The test apparatus performs preliminary actions by converting the digital input signal to an analogue reference signal using a DA converter before comparison. This preliminary conversion enables the system to work with analogue signals throughout the measurement process, allowing the use of a low-resolution AD converter while maintaining high measurement precision through the reference signal comparison method.
Solution Approach 2:
The patent implements a feedback mechanism where the analogue output signal from the device under test is compared with an analogue reference signal, and the difference is processed to determine defects. This feedback-based comparison method enables high-precision measurement even with a low-resolution AD converter by using the reference signal as a benchmark.
Data Source
AI summary
There is provided a test apparatus for testing a device under test, the test apparatus including: a test signal supplying section that supplies a digital input signal for testing purposes, to the device under test; a reference signal output section that outputs an analogue reference signal in accordance with the digital input signal; a difference obtaining section that outputs an analogue difference signal representing a difference between the analogue reference signal and an analogue output signal outputted by the device under test in accordance with the digital input signal; and a determining section that determines whether the analogue output signal shows a defect or not based on the analogue difference signal.