A/D Converter Testing via Pulse Delay Circuits
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Solution Overview
Problem
Existing A/D converter circuits require expensive high-accuracy evaluation devices and long testing times, especially for high-resolution applications, due to the need for extensive voltage step checking and increased comparator counts, which complicates efficient testing and increases costs.
Innovation Solution
A method utilizing pulse delay circuits or ring delay circuits with cascade-connected or ring-connected delay units and encoding circuits to count delay units or travel times within a shorter test-use sampling period, allowing for rapid and cost-effective testing by generating digital signals representing the input voltage, thereby determining the functionality of the A/D converter circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive voltage step checking is performed to test high-resolution A/D converter circuits, then measurement precision is improved, but loss of time increases significantly
Solution Approach 1:
The patent creates a simplified test model using a ring delay circuit that replicates the essential functionality of the A/D converter without requiring full-resolution voltage step checking. The ring delay circuit generates delay signals that correspond to different voltage levels, allowing the test to verify A/D converter functionality through signal timing rather than exhaustive voltage measurement, thus reducing testing time while maintaining adequate verification precision.
Solution Approach 2:
The patent changes the testing parameter from voltage magnitude measurement to time delay measurement. By converting the test approach to measure time delays in the ring delay circuit instead of performing extensive voltage step checks, the method achieves efficient verification of A/D converter performance without the time penalty of traditional high-precision voltage measurement methods.
2Measurement precision
If traditional testing methods with long sampling periods are used, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent employs periodic clock signals to drive the ring delay circuit and generate test patterns at high frequency. By using periodic action with short periods (high frequency clock signals), the system can perform multiple test cycles rapidly, significantly improving testing productivity compared to traditional methods that require long sampling periods for each measurement.
Solution Approach 2:
The ring delay circuit operates continuously with circulating delay signals, eliminating the need for repeated initialization and long sampling periods. The continuous operation allows multiple test points to be verified in sequence without interrupting the test flow, maintaining high productivity while ensuring adequate measurement precision through the continuous signal circulation.
3Measurement precision
If high-accuracy evaluation devices are used to test A/D converter circuits, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a ring delay circuit as an intermediary test device that simplifies the evaluation process. Instead of directly measuring complex A/D converter outputs with high-accuracy evaluation devices, the ring delay circuit converts the test into a simpler time delay measurement task, reducing the complexity and cost of required evaluation equipment while maintaining adequate measurement precision.
Solution Approach 2:
The patent replaces complex electronic measurement systems with a timing-based test approach. By substituting direct voltage measurement with time delay measurement through the ring delay circuit, the method reduces dependence on high-accuracy evaluation devices and allows the use of simpler, less expensive timing instruments to achieve adequate test precision.
Data Source
AI summary
For testing an A/D converter circuit including a pulse delay circuit constituted by a plurality of cascade-connected delay units, and an encoding circuit configured to count the number of the delay units through which the input pulse signal passes within a predetermined measuring time and to output a digital signal representing the counted number, the method includes the steps of setting the A/D converter circuit in a test mode where the measuring time is set at a short test-use sampling period, applying the input pulse signal to each of serial delay blocks each of which is constituted by a predetermined number of the delay units, and determining good and bad of the A/D converter circuit on the basis of digital signals outputted from the encoding circuit representing the numbers of the delay units through which the input pulse signal has passed within each of the serial delay blocks.