Integrator-Based Light Conversion for High Dynamic Range Readout
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light-to-digital converters for photoplethysmogram (PPG) and functional near-infrared spectroscopy (fNIRS) systems require high dynamic range and high power consumption, particularly due to the need for separate components for signal readout, analog-to-digital conversion, and noise handling.
Innovation Solution
A light-to-digital converter that integrates a signal readout frontend and analog-to-digital conversion into a single component, using an integrator for transimpedance amplification, noise anti-aliasing, and sampling, with a comparator to determine stopping points and a control unit for power management, reducing the number of components and power requirements while maintaining high dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate components are used for signal readout frontend and high-resolution analog-to-digital converter, then measurement precision is improved, but power consumption increases and device complexity increases
Solution Approach 1:
The patent combines the signal readout frontend and analog-to-digital conversion functions into a single integrated component. The integrator circuit performs both transimpedance amplification and analog-to-digital conversion simultaneously, eliminating the need for separate high-resolution ADC and readout circuits. This merging maintains the required dynamic range (>80 dB for PPG, >100 dB for fNIRS) while significantly reducing power consumption and device complexity.
Solution Approach 2:
The integrator circuit is designed to perform multiple functions: it acts as a transimpedance amplifier for signal conditioning, an anti-aliasing filter for noise reduction, and an analog-to-digital converter for signal digitization. This multi-functional design eliminates the need for multiple specialized components, achieving high dynamic range with reduced power consumption and simplified architecture.
2Measurement precision
If separate components are used for signal readout frontend and high-resolution analog-to-digital converter, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the signal readout frontend and high-resolution analog-to-digital converter into a single integrated integrator circuit. This consolidation maintains the required dynamic range performance while significantly reducing the number of discrete components needed in the system, thereby simplifying the overall device architecture.
Solution Approach 2:
The integrator circuit is designed as a universal component that simultaneously performs transimpedance amplification, anti-aliasing filtering, and analog-to-digital conversion. This multi-functionality eliminates the need for multiple specialized components, achieving high dynamic range with reduced device complexity.
3Measurement precision
If integration time is increased to improve measurement accuracy, then measurement precision is improved, but response speed deteriorates
Solution Approach 1:
The patent implements dynamic integration time adjustment where the integration period is adapted based on the detected signal characteristics and baseline level. The control unit dynamically modifies the integration time to optimize the balance between measurement precision and response speed, allowing the system to achieve high measurement accuracy while maintaining fast response capabilities.
Solution Approach 2:
The system employs feedback mechanisms where the measured signal and baseline level are continuously monitored. Based on this feedback, the control unit adjusts the integration time in real-time to maintain optimal measurement precision while ensuring fast response to changing physiological conditions. The feedback loop enables adaptive optimization of the integration period.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a high dynamic range of up to 119 dB with significantly reduced power consumption, compared to traditional systems, making it suitable for PPG and fNIRS applications.
Implementation Method 1
the light-to-current converter comprises a photodiode
Implementation Method 2
the light-to-current converter comprises a photomultiplier
Implementation Method 3
the integrator providing transimpedance amplification
Implementation Method 4
a current integrator, having an integrator output, integrating a current from a light-to-current converter
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
A light-to-digital converter (2) comprises a light-to-current converter (10); a current integrator (4) with an integrator output (30) resettable to a baseline level; and a counter (18) with a digital output (26), wherein the light-to-current converter (10) is switchably connectable as a positive integration input to the current integrator (4), for, during a light-collecting phase (404-406), integrating a current from the light-to-current converter (10), the integrator output (30) starting from the baseline value and ending at a value to be digitized; a reference current source (14) is switchably connectable as a negative integration input to the current integrator (4), for, during a counting phase (406-408) subsequent to the light-collecting phase (404-406), integrating a reference current from the reference current source (14), the integrator output (30) starting from the value to be digitized and ending at the baseline value, the time spent integrating the reference current corresponding to the value to be digitized; and the counter (18) is configured for measuring the time.