DAC Failure Detection Using Frequency Analysis of LSB Deviations
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Solution Overview
Problem
Conventional methods for detecting failures in digital-to-analog conversion circuits, particularly in the least significant bits, face challenges due to small deviations in output current, making accurate failure detection difficult.
Innovation Solution
A failure determination device that inputs a digital value to a DA conversion circuit, acquires a second digital value representing the difference between the circuit's output and a target output, and diagnoses failures based on the signal strength of an alternating-current component with a predetermined frequency, using a periodic function to enhance signal strength for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comparison circuit is used to detect failure by comparing voltage with a threshold, then the detection method is simple, but the determination accuracy is insufficient to detect small deviations in least significant bits
Solution Approach 1:
The patent applies periodic action by incrementing the digital value at regular time intervals and analyzing the AC component at a specific frequency that corresponds to this periodic input pattern. This transforms the static comparison problem into a dynamic frequency-domain analysis, enabling detection of small deviations that are modulated at the known input frequency. The periodic excitation allows the system to distinguish actual failure signals from noise by looking for responses at the expected frequency.
Solution Approach 2:
The patent replaces the simple voltage comparison method with a signal processing approach that analyzes the frequency characteristics of the output signal. Instead of directly comparing voltages in the time domain, the system transforms the problem into the frequency domain by examining the AC component at a predetermined frequency. This substitution enables more sensitive detection of small deviations while maintaining a relatively simple implementation structure.
2Measurement precision
If the sampling rate is increased to detect smaller deviations, then the detection accuracy improves, but the energy consumption increases
Solution Approach 1:
By using periodic action with a known input pattern, the patent enables the system to detect small deviations through frequency analysis rather than requiring high-speed continuous sampling. The system can use a lower sampling rate because it is looking for specific frequency components rather than trying to capture all possible variations. This reduces the computational burden and energy consumption associated with high-rate sampling and processing.
Solution Approach 2:
The patent changes the parameter being measured from the absolute voltage level to the frequency content of the voltage signal. By analyzing the AC component at a predetermined frequency rather than comparing instantaneous voltage values, the system achieves high detection accuracy with lower sampling rates. This parameter transformation allows the use of more energy-efficient processing methods that focus on extracting specific frequency information rather than processing the entire signal spectrum.
Data Source
AI summary
A failure determination device: acquires a second digital value indicating a difference between an analog electrical output generated by inputting a first digital value incremented at a first time interval to a DA conversion circuit and a target output indicated by the first digital value at a second time interval; and determines whether the DA conversion circuit has a failure based on a signal strength in a predetermined frequency of the second digital value that is a discrete signal.