SD-ADC Output Stability Detection Using Filtered Oscillation Thresholds
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Solution Overview
Problem
Detecting the stability or instability of a sigma delta analogue to digital converter (SD-ADC) output is challenging, as existing methods fail to reliably determine when the output can be trusted or not.
Innovation Solution
A detector comprising a filter arrangement and a threshold comparison element that filters the SD-ADC output to identify oscillations indicative of instability, using a frequency range of interest and a predetermined threshold to generate a flag signal indicating stability or instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the SD-ADC operates at high gain to improve signal conversion accuracy, then the conversion precision is improved, but the system becomes unstable and produces oscillations
Solution Approach 1:
The detector performs preliminary detection of oscillations in the digital output signal before the unstable signal is processed further. By filtering the digital output signal and comparing it against threshold values, the system identifies instability conditions in advance, allowing for preventive action or early warning before the unstable signal corrupts the final conversion result
Solution Approach 2:
A detector component is introduced as an intermediary between the SD-ADC and the output stage. This detector includes a filter arrangement and threshold comparison elements that monitor the digital output signal for oscillations indicative of instability, acting as a mediator that separates the high-gain conversion function from the stability monitoring function
2Reliability
If the detector monitors the entire frequency spectrum of the SD-ADC output, then detection completeness is improved, but the complexity of the filter arrangement increases
Solution Approach 1:
Instead of analyzing the entire frequency spectrum, the filter arrangement is designed to monitor specific frequency ranges where oscillations indicative of instability are most likely to occur. The filter arrangement includes a first filter and a second filter with different cutoff frequencies, creating localized monitoring zones that target critical oscillation frequencies while ignoring irrelevant spectral content
Solution Approach 2:
The frequency monitoring function is segmented into multiple filter stages. The filter arrangement divides the spectral analysis into separate filtering paths, each handling specific frequency bands. This segmentation allows the system to achieve comprehensive oscillation detection while keeping each individual filter component relatively simple
Data Source
AI summary
A detector comprising: a filter arrangement configured to receive an output from a sigma-delta analogue to digital, SD-ADC, converter and generate a filtered output; a threshold comparison element configured to receive the filtered output and determine if signal content present in the filtered output is above or below a predetermined threshold, and wherein the detector is configured to, based on the determination of the threshold comparison element, output a flag signal indicative of a determination that the output of the SD-ADC is one of stable or unstable.