Avalanche Diode Pulse Shaping for Photon Counting Accuracy
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Solution Overview
Problem
Existing photoelectric conversion devices with a stacked chip configuration struggle to efficiently count photons due to a large time constant at the output node of the diode, leading to inaccurate detection of photon incidence.
Innovation Solution
A photoelectric conversion device is designed with an avalanche amplification-type diode, a pulse shaping circuit, and a signal processing circuit, where the pulse shaping circuit is integrated into the first chip and the signal processing circuit into the second chip, allowing for accurate photon counting by reducing the time constant at the output node through a more efficient pulse conversion mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the junction between the first chip and the second chip corresponds to the output of the diode, then electrical connection between chips is simplified, but photon counting efficiency deteriorates due to large time constant
Solution Approach 1:
The patent segments the photoelectric conversion device into two separate chips: the first chip contains the photodiode and pulse shaping circuit, while the second chip contains the counter circuit. This segmentation allows the pulse shaping circuit to be positioned closer to the photodiode output, reducing the time constant and improving photon counting accuracy, while maintaining simplified inter-chip electrical connections through standardized bonding interfaces.
Solution Approach 2:
The pulse shaping circuit acts as an intermediary component between the photodiode and the counter circuit. By placing this circuit on the first chip closer to the photodiode output, it shapes the output signal before transmission to the second chip, effectively reducing the time constant and improving measurement precision without complicating the overall system architecture.
2Ease of manufacture
If the pulse shaping circuit is placed on the second chip, then chip fabrication is simplified, but signal processing efficiency deteriorates due to increased time constant
Solution Approach 1:
The patent divides the device into two functional chips with the pulse shaping circuit on the first chip and the counter circuit on the second chip. This segmentation optimizes signal processing speed by minimizing the time constant in the first chip while maintaining fabrication simplicity through standardized chip designs and bonding interfaces.
Solution Approach 2:
The patent changes the physical location of the pulse shaping circuit from the second chip to the first chip, fundamentally altering the signal transmission path and reducing the time constant. This parameter change (positioning) improves signal processing efficiency while the modular chip design maintains ease of manufacture.
3Device complexity
If the output node of the diode has a large time constant, then signal transmission between chips is simplified, but photon incidence detection accuracy deteriorates
Solution Approach 1:
The patent extracts the pulse shaping function from the second chip and places it on the first chip closer to the photodiode output. This extraction reduces the time constant at the output node, improving photon incidence detection accuracy, while the simplified inter-chip connection structure is maintained through standardized bonding interfaces.
Solution Approach 2:
The pulse shaping circuit serves as an intermediary that processes the photodiode output signal before transmission to the second chip. By positioning this intermediary circuit on the first chip, the patent reduces the time constant and improves detection accuracy without complicating the signal transmission path between chips.
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 configuration enables accurate detection of photon incidence by reducing the time constant at the output node, allowing for precise counting and conversion of photon signals into digital outputs.
Implementation Method 1
a photoelectric conversion device that digitally counts the number of photons reaching a photodiode
Implementation Method 2
an avalanche amplification-type diode
Data Source
AI summary
A photoelectric conversion device includes: an avalanche amplification-type diode; a pulse shaping circuit that shapes output from the avalanche amplification-type diode into a pulse; and a signal processing circuit that processes a signal corresponding to output from the pulse shaping circuit. A first base body in which the avalanche amplification-type diode is provided and a second base body in which the signal processing circuit is provided are stacked on each other, and the pulse shaping circuit is provided in the first base body.