Multi-Slope ADC Switching for SNR and Conversion Accuracy
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Solution Overview
Problem
Multi-channel analog-to-digital converters face errors in digital signal generation due to variations in slope signal gradients and offset voltages, limiting the accuracy of analog-to-digital conversion and signal-to-noise ratio improvement.
Innovation Solution
The proposed analog-to-digital converter employs multiple slope generators and comparators to generate digital signals based on reference signals, allowing for selection between a first mode for multiple channel conversion and a second mode for higher accuracy with fewer channels, using a combination of course and fine AD conversion processing to improve accuracy without increasing circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple channels are used to improve signal-to-noise ratio, then S/N ratio improves by √M times, but analog-to-digital conversion accuracy deteriorates due to variations in slope signal gradient and offset voltage
Solution Approach 1:
The conversion process is segmented into two distinct modes: a first mode for multi-channel parallel conversion and a second mode for high-accuracy sequential conversion. The system divides the conversion task and selects the appropriate mode based on whether accuracy or S/N ratio improvement is the priority, thereby resolving the contradiction between these two requirements.
Solution Approach 2:
The analog-to-digital converter dynamically switches between two operational modes depending on the application requirements. In the first mode, multiple channels operate in parallel for improved S/N ratio. In the second mode, a single channel performs sequential conversion with higher accuracy. This dynamic adaptability allows the system to optimize performance for different scenarios.
2Reliability
If the number of channels increases to M times, then signal power becomes M times and S/N ratio improves, but circuit complexity increases
Solution Approach 1:
The analog-to-digital converter is designed with multi-functionality, capable of operating in two distinct modes using the same hardware resources. The first mode utilizes multiple channels for high signal power applications, while the second mode uses sequential conversion for high accuracy applications. This universality allows the system to achieve different performance goals without requiring separate dedicated circuits for each function.
Solution Approach 2:
The system changes operational parameters by switching between two modes: in the first mode, multiple channels are activated simultaneously to increase signal power; in the second mode, the system transitions to sequential single-channel conversion to reduce circuit complexity while maintaining high accuracy. This parameter change allows flexible adaptation to different performance requirements.
3Object-affected harmful factors
If differential output detection is used to remove in-phase noise, then distortion is reduced, but quantization noise cannot be reduced
Solution Approach 1:
The invention segments the noise handling approach by implementing two distinct conversion modes. The first mode addresses in-phase noise through differential output detection, while the second mode specifically targets quantization noise reduction through sequential conversion with oversampling and averaging. This segmentation allows each mode to address specific noise types effectively.
Solution Approach 2:
In the second mode, the system employs feedback through oversampling and averaging of multiple conversion results. By performing multiple conversions and averaging the results, the system reduces quantization noise through statistical feedback, complementing the differential detection approach used in the first mode.
Data Source
AI summary
An analog-to-digital converter has a first digital signal generator that generates a first digital signal based on whether or not a sampling signal of an input signal is equal to or lower than a signal corresponding to a second reference signal higher than a first reference signal, a first slope generator to generate a first slope signal that changes with time from the sampled and held signal equal to or lower than the first reference signal, a second slope generator to generate a second slope signal that changes with time from the sampled and held signal to a signal level equal to or lower than the second reference signal, and a second digital signal generator that generates a second digital signal based on a time at which the first slope signal matches the first reference signal or a time at which the second slope signal matches the second reference signal.