Distance Sensor Readout Using Variable Potential Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for reading out demodulation pixels in distance sensors are inefficient in processing signals quickly and accurately, particularly in suppressing background noise, which affects the detection of low-intensity optical signals.
Innovation Solution
The method involves changing the height of the potential barrier formed by the transfer gate and the well depth of the storage gate, allowing for independent determination of charge carrier differences without relying on the total charge quantity, and applying a variable control voltage to effectively stop charge transfer between storage and floating diffusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the well depth of storage gates is reduced until charge carriers can overcome the potential barrier, then charge carriers can be transferred to floating diffusion for measurement, but the processing time increases and background noise suppression becomes inefficient
Solution Approach 1:
The patent applies dynamics by making the potential barrier height variable rather than fixed. The control voltage applied to the transfer gate is dynamically adjusted during the readout process, allowing the system to optimize both transfer efficiency and timing. This dynamic control enables faster charge carrier transfer while maintaining effective background noise suppression through the dual-parameter control method.
Solution Approach 2:
The patent changes physical parameters by simultaneously controlling both the well depth and the potential barrier height. Instead of relying solely on reducing well depth to enable charge transfer, the invention introduces an additional control dimension by varying the potential barrier height through adjustable control voltage. This dual parameter control allows independent optimization of transfer speed and noise suppression performance.
2Measurement precision
If a fixed potential barrier is used in the transfer gate, then the device structure remains simple, but the ability to independently determine charge carrier differences without relying on total charge quantity is limited
Solution Approach 1:
The transfer gate structure serves multiple functions: it acts as both a potential barrier and a controllable release mechanism. By applying variable control voltage to the same transfer gate, the system achieves both charge carrier transfer and background noise suppression without requiring separate dedicated structures. This multi-functionality enables precise charge carrier difference determination while maintaining relatively simple device architecture.
3Productivity
If the well depth is continuously reduced to transfer charge carriers, then all charge carriers can be transferred, but the processing speed decreases and capacity requirements increase
Solution Approach 1:
The patent applies partial action by transferring only the necessary portion of charge carriers rather than continuously reducing well depth to transfer all carriers. The variable potential barrier allows selective and controlled charge carrier transfer, enabling faster processing of the relevant signal portion without requiring excessive capacity for storing and processing all possible charge carriers.
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 approach enables faster signal processing, improved accuracy, and effective suppression of background noise, allowing for the detection of low-intensity optical signals with reduced capacity requirements and without fundamental changes to existing detector layouts.
Implementation Method 1
changing the height of the potential barrier that is formed by the transfer gate
Implementation Method 2
the well depth of the storage gates is changed in addition to the height of the potential wall of the transfer gate
Implementation Method 3
the incident photons inducing mobile charge carriers in the photodetector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for reading a demodulation pixel (1) of a distance sensor for determining a distance, in particular for determining the difference between two charge quantities (11A, 11B) independent of the total amount of the charge quantities (11A, 11B), is proposed, as well as a distance sensor. For faster signal processing, a variable control voltage is applied to the transfer gates (5A, 5B) to influence the potential barrier (4A, 4B), and the respective potential barriers (4A, 4B) of the corresponding transfer gates (5A, 5B) are lowered before or until charge carriers from the storage gates (2A, 2B) can overcome the respective potential barrier (4A, 4B) of the corresponding transfer gate (5A, 5B) and pass through to the associated floating diffusion (6A, 6B).