Avalanche Photodiode Array Clock Distribution for Time Resolution
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Solution Overview
Problem
In photodetector devices with two-dimensionally arranged avalanche photodiodes, the non-constant wiring distance from the clock driver to time measurement circuits leads to waveform collapse of high-frequency clock signals, resulting in inaccurate pulse signal detection and increased power consumption due to dark counts, especially as the detection surface area increases.
Innovation Solution
A photodetector device design featuring a compound semiconductor avalanche photodiode array substrate mounted on a circuit substrate with integrated delay line units and quenching circuits, where the clock driver is separate from the avalanche photodiodes, reducing wiring length and heat transfer, and utilizing a counter and control circuit to enhance time measurement accuracy and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frequency of the clock signal is increased to improve time resolution, then time resolution is improved, but waveform collapse occurs in time measurement circuits due to longer wiring distances
Solution Approach 1:
The patent divides the detection surface into multiple regions, each with its own time measurement circuit that is locally coupled to the clock driver. This segmentation reduces the wiring distance for each circuit while maintaining overall system coverage, preventing waveform collapse in high-frequency clock signals.
Solution Approach 2:
The patent introduces a column-direction clock distribution path in addition to the row-direction path. By distributing clock signals in both row and column directions through intersection points, the system reduces wiring distances and enables higher clock frequencies without waveform collapse.
2Area of stationary object
If the area of the detection surface is increased, then detection coverage is improved, but wiring distance from clock driver to time measurement circuits increases
Solution Approach 1:
The patent segments the large detection surface into multiple smaller regions, each with its own time measurement circuit locally coupled to the clock driver. This segmentation allows the system to maintain short wiring distances while covering a large overall area.
Solution Approach 2:
The patent adds a column-direction clock distribution dimension to the existing row-direction distribution. This two-dimensional clock distribution approach enables coverage of larger detection surfaces while keeping individual wiring segments short.
3Measurement precision
If the frequency of the clock signal is increased, then time resolution is improved, but power consumption and heat generation from the clock driver increase
Solution Approach 1:
The patent segments the clock distribution into multiple local regions, each with its own time measurement circuit. This segmentation allows the system to use lower clock frequencies in each local region while achieving the required time resolution, thereby reducing overall power consumption and heat generation.
Solution Approach 2:
The patent introduces column-direction clock distribution as an additional dimension. This enables the system to achieve high time resolution through multiple lower-frequency clock signals distributed in two dimensions, rather than using a single high-frequency signal, thus reducing power consumption.
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 design ensures accurate detection of pulse signals across larger detection surfaces with improved time resolution and reduced power consumption, minimizing erroneous measurements and dark count noise.
Implementation Method 1
a plurality of avalanche photodiodes are two-dimensionally arranged in the avalanche photodiode array substrate. The plurality of avalanche photodiodes is arranged to operate in a Geiger mode
Implementation Method 2
Each of the time measurement circuits includes a delay line unit including delay line constituted by a plurality of delay elements which are connected in series
Data Source
AI summary
A photodetector device includes an avalanche photodiode array substrate. A circuit substrate includes time measurement circuits and a clock driver. Each of the time measurement circuit includes a delay line unit, and is arranged to acquire, from an operation result of a delay line, time information indicating timing at which a pulse signal is input from a corresponding avalanche photodiode. The delay line unit is arranged to initiate an operation of the delay line in response to input of the pulse signal to the time measurement circuit, and to stop the operation of the delay line in response to input of a clock signal from a clock driver to the time measurement circuit, and is arranged to detect a time interval shorter than a cycle of the clock signal by the operation of the delay line.