Per-Pixel ADC Circuit With Serial DAC for Compact X-Ray Detectors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pixel detectors for radiation detection face limitations in conversion efficiency and spatial resolution due to indirect X-ray imaging processes, and existing ADC designs struggle to achieve high resolution and low power consumption in compact form factors.
Innovation Solution
The development of a pixel detector circuit incorporating a unity-gain buffer, high-gain comparator, and capacitor trimming circuit with sub-fF precision, along with shared logic circuitry for area and power savings, utilizing high-performance followers and transistors to achieve zero input capacitance and wide signal range, enabling efficient direct conversion of X-rays into electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect X-ray imaging process is used with scintillation layer and photodiodes, then X-ray photons can be converted into visible photons and detected, but conversion efficiency is limited and spatial resolution is reduced due to losses and scattering
Solution Approach 1:
The patent removes the scintillation layer from the imaging system and uses semiconductor absorbers for direct conversion of X-rays into electron-hole pairs, eliminating the intermediate conversion step that causes energy loss and spatial resolution degradation
Solution Approach 2:
The patent replaces the optical conversion mechanism (scintillation + photodiode detection) with a direct electrical conversion mechanism using semiconductor absorbers, achieving superior sensitivity and spatial resolution
2Area of stationary object
If ADC circuit is made compact to reduce chip area, then chip area is reduced, but achieving high resolution and low power consumption becomes difficult
Solution Approach 1:
The patent combines the ADC circuit with the pixel sensor in a fully integrated hybrid pixel detector, sharing common structures and processes between the semiconductor absorber and the readout electronics to reduce overall chip area while maintaining high resolution
Solution Approach 2:
The patent designs the ADC circuit to perform multiple functions including signal amplification, noise filtering, and digital conversion within a single integrated structure, reducing the need for separate dedicated circuits and minimizing chip area
3Area of stationary object
If ADC circuit is made compact to reduce chip area, then chip area is reduced, but power consumption control becomes challenging
Solution Approach 1:
The patent employs periodic sampling and resetting of the pixel detector circuit, allowing the ADC to remain in a low-power state between measurements and only become active when new X-ray events occur, thereby reducing average power consumption in the compact design
Solution Approach 2:
The patent implements automatic gain control and adaptive threshold adjustment within the ADC circuit, allowing the system to self-optimize its performance for different X-ray flux conditions without external intervention, maintaining low power consumption across varying operational scenarios
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 solution enhances the sensitivity, spatial, and temporal resolution of pixel detectors while reducing power consumption and chip area, facilitating the detection of X-ray photon energies with improved dynamic range and efficiency.
Implementation Method 1
semiconductor absorbers permit the direct conversion of X-rays into electron-hole pairs, which can then be measured as an electrical signal by readout electronics
Data Source
AI summary
A compact ADC circuit can include one or more comparators, and a serial DAC (Digital-to-Analog) circuit that provides a signal to the comparator (or comparators). In addition, the ADC circuit can include a serial DAC redistribution sequencer that can provide a plurality of signals as input to the serial DAC circuit and is subject to a redistribution cycle and which receives as input a signal from a data multiplexer whose input connects electronically to an output of the comparator. The circuit can further include an ADC code register that provides an ADC output that connects electronically to the output of the comparator and the input to the data multiplexer. Shared logic circuitry for sharing common logic between pixels can be included, wherein the shared logic circuitry connects electronically to the data multiplexer and the ADC code register, wherein the shared logic circuitry promotes area and power savings for the pixel detector circuit.