Adaptive SPAD Read-Out for Wider Dynamic Range
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Solution Overview
Problem
Existing SPAD-based radiation sensors face limitations in dynamic range due to noise, circuitry capacity, and device size, which compromise signal-to-noise ratio and require additional components, especially in applications like Point of Care testing and Electronic-Nose applications.
Innovation Solution
A radiation-sensitive device with a plurality of SPADs and adaptive read-out circuitry that adjusts the read-out rate based on incident radiation intensity, minimizing the number of SPADs used and increasing the dynamic range while maintaining signal-to-noise ratio through programmable thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of SPADs is used to improve signal-to-noise ratio at low radiation levels, then signal-to-noise ratio is improved, but device complexity and circuitry capacity increase
Solution Approach 1:
The patent implements dynamic adaptation of the read-out rate based on incident radiation intensity. The circuitry monitors radiation levels and adjusts the read-out rate accordingly - using higher read-out rates at low radiation levels to maintain signal-to-noise ratio, and lower read-out rates at high radiation levels to prevent saturation. This dynamic operation allows the system to achieve high reliability across varying conditions without requiring a permanently oversized SPAD array and associated circuitry.
2Measurement precision
If the read-out rate is kept low to capture all photon strikes, then detection completeness is improved, but dynamic range is limited at high radiation intensities
Solution Approach 1:
The system dynamically adjusts the read-out rate based on incident radiation intensity. At low radiation levels, a high read-out rate ensures complete photon capture and high detection completeness. At high radiation levels, the read-out rate is reduced to match the photon arrival rate, preventing saturation and extending the measurable dynamic range. This dynamic adaptation resolves the contradiction between detection completeness and dynamic range.
Solution Approach 2:
The patent changes the operational parameter (read-out rate) based on the incident radiation intensity. By monitoring radiation levels and adjusting the read-out rate accordingly, the system adapts its detection capabilities to match the current signal conditions, enabling it to maintain measurement precision across a wide dynamic range from very low to very high radiation intensities.
3Adaptability or versatility
If additional components like pinholes are added to reduce radiation intensity, then dynamic range is improved, but device size and complexity increase
Solution Approach 1:
The patent replaces mechanical/optical components (pinholes, stacked apertures) with an electronic control mechanism. Instead of using physical structures to attenuate radiation, the system uses electronic adjustment of the read-out rate to adapt to different radiation intensities. This substitution eliminates the need for additional mechanical components, reducing device size and complexity while maintaining extended dynamic range capability.
4Adaptability or versatility
If the read-out rate is increased to handle high radiation intensity, then dynamic range is improved, but signal-to-noise ratio deteriorates at low radiation levels
Solution Approach 1:
The system implements dynamic read-out rate adjustment that responds to incident radiation intensity. When radiation levels are low, the read-out rate is increased to ensure sufficient sampling and maintain signal-to-noise ratio. When radiation levels are high, the read-out rate is decreased to prevent saturation and handle the elevated photon flux. This dynamic adaptation allows the system to optimize for either signal-to-noise ratio or dynamic range depending on current conditions, resolving the contradiction between these two performance metrics.
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 adaptive read-out rate allows the device to maintain signal-to-noise ratio and increase dynamic range by optimizing the number of SPADs read-out, reducing missed photon strikes and overall device size.
Implementation Method 1
Single Photon Avalanche Diode (SPAD) based photon counters offer the ability to detect very low levels of radiation by counting individual photons
Data Source
AI summary
A radiation-sensitive device is disclosed. The device comprises a plurality of single photon avalanche diodes (SPADs) and circuitry configured to adapt a read-out rate of the plurality of SPADs in relation to an intensity of incident radiation. Also disclosed is an associated method of increasing a dynamic range of a radiation-sensitive device comprising a plurality of SPADs. The method comprises adapting a read-out rate of the plurality of SPADs in relation to an intensity of incident radiation.