Analog Accumulator X-ray Photon Counting Pixel
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Solution Overview
Problem
Existing X-ray detection technologies face challenges with high complexity and power consumption in photon counting methods due to the need for large digital counters, which limits dynamic range and increases noise in X-ray image sensing.
Innovation Solution
A pixel design that employs an analog accumulator to convert X-ray radiation into a non-linear pulse train, using comparators and a multiplexer to accumulate pulses, providing natural overflow prevention and tunable non-linearity, thereby reducing the complexity and noise associated with digital counters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting method is used, then measurement precision is improved, but device complexity increases due to large digital counters
Solution Approach 1:
The patent replaces complex digital counters with an analog accumulator that integrates photon pulse signals directly in the analog domain. This substitution eliminates the need for elaborate digital counting circuits while maintaining photon counting precision, thereby reducing device complexity.
Solution Approach 2:
The patent introduces an analog accumulator as an intermediary component between the photon detector and the output stage. This accumulator integrates the pulse train signals analogously, serving as a mediator that simplifies the overall system architecture by eliminating the need for complex digital counters.
2Measurement precision
If digital counter is used, then photon counting accuracy is improved, but power consumption increases
Solution Approach 1:
The patent substitutes power-hungry digital counters with a low-power analog accumulator that performs integration in the analog domain. This replacement maintains photon counting accuracy while significantly reducing power consumption by eliminating the need for complex digital logic circuits.
3Measurement precision
If digital counter is used, then photon counting is achieved, but noise increases
Solution Approach 1:
The patent replaces digital counters that introduce read noise with an analog accumulator that integrates signals in the analog domain before digitization. This substitution maintains photon counting capability while eliminating the analog read noise that would otherwise be introduced by digital counter circuits.
4Measurement precision
If analog accumulator with non-linear response is used, then dynamic range is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the inherent non-linear response characteristics of the analog accumulator circuit to extend the dynamic range. By deliberately designing the circuit to exhibit non-linear behavior, the system can accommodate a wider range of signal intensities, from very weak to very strong photon fluxes, while managing manufacturing precision through circuit design rather than component tolerances.
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 higher dynamic range and lower noise levels, enabling effective photon counting with reduced power consumption and complexity, while maintaining energy discrimination capabilities.
Implementation Method 1
The image sensor 10 illustrated comprises a phototransducer such as a photodiode 11, for converting the impinging radiation 12 into an electrical signal
Implementation Method 2
where the X-ray photon is absorbed in a scintillator material where it creates a flash of secondary, visible light
Data Source
AI summary
A pixel for the detection of electromagnetic radiation or impinging high energy particles, in particular for detecting X-ray photons, including a radiation receptor for converting the electromagnetic radiation or impinging high energy particles into a radiation signal, a converter for converting the radiation signal into a pulse train, and an analog accumulator for accumulating the pulses of a pulse train to an analog signal for readout. The analog accumulator is adapted such that the analog signal is non-linearly proportional to the pulse count. Such non-linear analog accumulator has the advantage of an large dynamic range.