ADC Coarse-Fine Conversion for Fast Settling of Multiplexed Signals
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Solution Overview
Problem
Existing analog-to-digital converter (ADC) technologies face challenges in quickly settling on digital values for multiplexed analog signals with large variations in DC offset, particularly in sensor systems like neural probes, where efficient signal processing is crucial for high spatial resolution and minimal tissue damage.
Innovation Solution
The proposed ADC module operates in a coarse conversion phase to quickly determine an initial digital value and a fine conversion phase using a delta modulation loop to track the signal, allowing for rapid adaptation to changes in DC offset, with the option to re-initiate coarse conversion if significant deviations occur, and utilizing shared components for both phases to maintain compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If delta modulation is used in the ADC circuitry to achieve a large dynamic range, then the dynamic range is improved, but the processing time increases before the modulator reaches the input voltage level of a new sub-sequence
Solution Approach 1:
The patent divides the analog-to-digital conversion process into two distinct phases: a coarse conversion phase that quickly establishes the baseline voltage level, and a fine conversion phase that performs precise delta modulation. This segmentation allows the system to rapidly adapt to new sub-sequences by first capturing their approximate level through coarse conversion, then applying high-precision delta modulation only when needed, thereby reducing the overall processing time while maintaining large dynamic range capability.
Solution Approach 2:
The coarse conversion phase acts as a preliminary action that prepares the ADC circuitry for subsequent fine conversion by quickly determining the baseline voltage level of incoming sub-sequences. This preliminary measurement enables the delta modulation to start from an accurate reference point, significantly reducing the time required for the modulator to reach the input voltage level of new sub-sequences while preserving the large dynamic range benefit.
2Area of stationary object
If a single ADC circuitry is used to process multiple multiplexed signals, then the area consumption is reduced, but the ability to quickly settle on digital values for signals with large DC offset variations deteriorates
Solution Approach 1:
The patent segments the conversion process into coarse and fine phases, where the coarse phase rapidly captures the DC offset level of multiplexed signals and the fine phase performs precise conversion. This temporal segmentation enables a single ADC circuitry to quickly settle on digital values for signals with large DC offset variations by first establishing the baseline through coarse conversion, then applying high-speed delta modulation, thereby maintaining area efficiency while improving settling speed.
Solution Approach 2:
The patent implements dynamic switching between coarse conversion mode and fine conversion mode based on the characteristics of incoming multiplexed signals. When large DC offset variations are detected in new sub-sequences, the system dynamically transitions to coarse conversion to quickly establish the new baseline, then switches to fine conversion for precise processing. This dynamic adaptation allows a single ADC circuitry to maintain fast settling speed across multiple multiplexed signals with varying DC offsets while consuming minimal area.
Data Source
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AI summary
An analog-to-digital converter, ADC, module (110) is configured to operate in a coarse conversion ADC phase, and a fine conversion ADC phase comprising a delta modulation loop for tracking a signal, wherein the ADC module (110) is configured to, at initiation of input of an analog signal, operate in the coarse conversion ADC phase for determining a coarse digital value; wherein the ADC module (110) is configured to, when the coarse digital value is determined, operate in the fine conversion ADC phase, receive the coarse digital value as an initial approximation of the analog signal and track the analog signal during a finite duration.