Optical Proximity Detector with Shared Signal Processing Circuitry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical proximity detectors consume high power, are large in size, and costly, especially when used in mobile devices that are battery-powered and small in size, due to the need for sequential analog-to-digital conversions and potential inaccuracies in comparing signals from multiple photodetectors.
Innovation Solution
A shared transimpedance amplifier, programmable gain amplifier, and analog-to-digital converter circuitry, along with a comparator and multiplexer, allow for simultaneous comparison and selection of current signals from multiple photodetectors, reducing power consumption and size by eliminating the need for sequential conversions and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sequential analog-to-digital conversions are used for multiple photodetectors, then device complexity is reduced, but power consumption increases and measurement precision decreases
Solution Approach 1:
The patent combines multiple photodetectors with their respective transimpedance amplifiers, programmable gain amplifiers, and analog-to-digital converters into a single integrated circuit device. This merging eliminates the need for sequential conversions by providing dedicated conversion paths for each photodetector, simultaneously reducing power consumption and maintaining measurement precision while keeping the device structure compact.
2Measurement precision
If multiple photodetectors with dedicated conversion circuits are used, then measurement precision improves, but device complexity and size increase
Solution Approach 1:
The patent integrates multiple complete signal processing chains (photodetector + transimpedance amplifier + programmable gain amplifier + analog-to-digital converter) into a single monolithic integrated circuit. This merging approach maintains dedicated conversion paths for each photodetector to preserve measurement precision while eliminating the need for external discrete components, thereby reducing overall device complexity.
Solution Approach 2:
The integrated circuit is designed with universal signal processing blocks that can handle multiple photodetector inputs simultaneously. Each photodetector channel shares the same types of processing circuits (transimpedance amplifier, programmable gain amplifier, ADC), allowing the device to maintain high measurement precision for multiple sensors without proportionally increasing complexity.
3Measurement precision
If multiple photodetectors with dedicated conversion circuits are used, then measurement precision improves, but device size increases
Solution Approach 1:
The patent consolidates multiple photodetectors and their complete signal processing chains into a single integrated circuit package. By merging all necessary components (photodetectors, transimpedance amplifiers, programmable gain amplifiers, and analog-to-digital converters) into one compact unit, the device achieves high measurement precision through dedicated conversion paths while minimizing overall device volume.
Solution Approach 2:
The integrated circuit employs a nested structure where multiple photodetector channels are embedded within a shared processing architecture. Each photodetector channel contains nested functional blocks (transimpedance amplifier nested within the signal path, programmable gain amplifier nested within the conversion chain, ADC nested within the processing pipeline), allowing compact packaging that maintains measurement precision while reducing device size.
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
This configuration reduces power consumption, size, and cost while maintaining accuracy by enabling simultaneous signal processing across multiple photodetectors, enhancing the performance and efficiency of optical proximity detectors.
Implementation Method 1
a first photodetector (PD) produces a first current detection signal in response to light incident on and detected by the first PD
Implementation Method 2
a transimpedance amplifier converts the current detection signal to a voltage detection signal
Data Source
AI summary
An optical proximity detector includes a plurality photodetectors (PDs) and a winner-take-all (WTA) circuit. Each of the PDs has a respective field of view (FOV) and produces a respective analog current detection signal indicative of light incident on and detected by the PD. In an embodiment, the WTA circuit includes a comparator and a multiplexor (MUX). The comparator compares the analog current detection signals produced by the PDs and produces a selection signal in dependence thereon. The MUX receives the analog current detection signals produced by the PDs and outputs one of the analog current detection signals in dependence on the selection signal produced by the comparator. Circuitry, which is shared by the PDs, produces a digital detection signal corresponding to the one of the analog current detection signals output by the MUX. Such design can be used to reduce power consumption, size and cost of an optical proximity detector.