CSA-ADC Pixel Readout With ANN X-Ray Pulse Estimation
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Solution Overview
Problem
Existing X-ray photon detection systems, particularly hybrid pixel array detectors (HPADs), face challenges in accurately measuring voltage pulse amplitudes due to technology spread, gain nonlinearity, DC offset fluctuations, and pixel analog front-end noise, which affect the precision of photon energy estimation.
Innovation Solution
Incorporating an artificial neural network (ANN) block, specifically a multi-layer perceptron (MLP) neural network, within the pixel readout channel to enhance the estimation of voltage pulse amplitudes by processing sampled codewords, utilizing a charge-sensitive amplifier (CSA), analog-to-digital converter (ADC), and ANN modules for precise photon energy measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional threshold-based discrimination is used for photon detection, then the device complexity is low, but the measurement precision of voltage pulse amplitude is degraded due to technology spread, gain nonlinearity, DC offset fluctuations, and noise
Solution Approach 1:
The patent transforms the detection approach from simple threshold comparison to measuring the time interval between threshold crossings. This parameter transformation converts amplitude measurement (affected by noise and offset) into time measurement (more precise and noise-resistant), thereby improving measurement precision without proportionally increasing device complexity
Solution Approach 2:
The patent replaces the traditional analog threshold discrimination method with a time-interval measurement system using T0 and T1 markers. This substitution transforms the measurement mechanism from direct amplitude comparison to temporal measurement, achieving higher precision while managing complexity through systematic design
2Measurement precision
If threshold trimming is applied to minimize DC offset dispersion, then the measurement precision improves, but the ease of operation decreases due to additional configuration requirements
Solution Approach 1:
The system performs self-calibration by automatically determining optimal threshold levels through time-interval measurements. The T0 marker captures the leading edge while T1 captures the trailing edge, and the system autonomously processes these intervals to compensate for DC offset variations, eliminating manual threshold trimming operations
Solution Approach 2:
The patent implements preliminary time-interval measurement between T0 and T1 markers before final photon energy calculation. This preliminary action pre-compensates for DC offset effects and noise, so that subsequent energy estimation operates on already-corrected data, improving precision without requiring manual intervention
3Reliability
If analog threshold comparison is used for photon detection, then the device complexity is low, but the reliability of photon hit detection is degraded due to noise and DC level fluctuations
Solution Approach 1:
The patent replaces unreliable analog threshold comparison with a time-interval measurement system. By measuring the time between T0 (leading edge) and T1 (trailing edge) marker crossings, the system achieves noise-resistant detection that reliably identifies photon hits even in noisy conditions, with processing complexity managed through systematic marker generation and interval calculation
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 ANN-based solution significantly improves the precision of photon energy measurement, enabling high-resolution detection suitable for color X-ray imaging and spectrometer applications.
Implementation Method 1
a charge-sensitive amplifier (CSA) block that amplifies a current pulse carried to its input from the pixel electrode and converts it to a voltage pulse
Implementation Method 2
an analog-to-digital converter (ADC) block that samples the voltage pulse and outputs the result of sampling as codewords
Data Source
AI summary
A circuit for an X-ray-induced voltage pulse amplitude estimation inside a pixel readout channel, in a hybrid pixel array detector, an input of the circuit is connected to a pixel electrode, is provided. The circuit including a charge-sensitive amplifier (CSA) block configured to amplify a current pulse carried to its input from the pixel electrode and to convert it to a voltage pulse; an analog to digital converter (ADC) block connected to an output of the CSA block and configured to operate at a first clock frequency, and to sample an input voltage signal and output a result of the sampling as a codeword, wherein an artificial neural network (ANN) block is configured to operate at a second clock frequency, and to perform operations related to the neural network and estimate an amplitude of the voltage pulse, the ANN block in communication with the ADC block.