Photon Counting Circuit With Dynamic Noise Shaping and Low Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photon counting systems in CT imaging consume excessive power due to the need for high bandwidth amplifiers to meet noise specifications, which is inefficient and not effectively managed.
Innovation Solution
A circuit incorporating a charge sensitive amplifier, high pass filter, active comparator, and noise reduction circuit that dynamically filters noise by activating the ADC only when light is received, preventing low and high frequency noise from reaching the converter, thus reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high bandwidth amplifier is used to obtain spectral information, then measurement precision is improved, but use of energy increases significantly
Solution Approach 1:
The patent extracts and removes the high bandwidth amplifier from the photon counting system. Instead of using a high bandwidth amplifier to achieve spectral information, the system directly counts photons and measures their energies using a different architecture that doesn't require the high bandwidth amplification stage, thereby eliminating the excessive power consumption while maintaining measurement precision.
Solution Approach 2:
The patent replaces the conventional electronic amplification mechanism with a direct photon counting and energy measurement approach. Instead of amplifying the electrical signal through a high bandwidth amplifier, the system uses specialized photodetectors and signal processing circuits that directly measure photon energies, substituting the mechanical/electronic amplification system with a more efficient measurement system.
2Measurement precision
If noise filtering is applied continuously, then measurement precision is improved, but use of energy increases due to continuous ADC operation
Solution Approach 1:
The patent implements periodic action by enabling the ADC and noise filtering only during specific time windows when photons are actually detected. The system uses a trigger mechanism that activates the ADC and filtering circuits only when a photon event occurs, rather than operating continuously. This periodic operation maintains measurement precision during detection events while dramatically reducing power consumption during idle periods.
Solution Approach 2:
The system employs self-service through automatic trigger-based activation. When a photon detection event occurs, the system automatically activates the ADC and noise filtering circuits without requiring continuous external control. The dead time management is also self-regulating, ensuring that the system only processes signals when necessary, thereby reducing power consumption while maintaining measurement precision.
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 improves signal gain, reduces noise, and maintains constant dead time, enhancing the signal-to-noise ratio without additional power consumption, thereby optimizing the imaging system's performance.
Implementation Method 1
A photodiode generates a current signal in response to incident light
Data Source
AI summary
In described examples, a charge sensitive amplifier (CSA) generates an integrated signal in response to a current signal. A high pass filter is coupled to the CSA and receives the integrated signal and an inverse of an event signal, the high pass filter generates a coarse signal. An active comparator is coupled to the high pass filter and receives the coarse signal and a primary reference voltage signal, the active comparator generates the event signal.