Solid State Imaging Device Parallel ADC Signal Division
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Solution Overview
Problem
Conventional time of flight (TOF) solid state imaging devices require a holding unit for information in each pixel, which complicates distance measurement by necessitating linear sequential reading of distance measurement light and analog memory for each pixel.
Innovation Solution
A solid state imaging device with a light receiving unit, a dividing unit that allocates pixel signals to multiple AD converters for digital conversion, and an in-phase component removal unit, eliminating the need for a holding unit by dividing and processing pixel signals efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a holding unit is added to each pixel to store distance measurement information, then the measurement capability is improved, but the device complexity increases due to requiring analog memory and linear sequential reading
Solution Approach 1:
The pixel signal processing is segmented into multiple parallel ADC converters instead of using a single holding unit per pixel. Each pixel signal is divided and processed by multiple ADCs simultaneously, eliminating the need for analog memory while maintaining distance measurement capability through parallel digital conversion paths
Solution Approach 2:
The analog memory holding unit is replaced with a digital processing system using multiple ADC converters. The continuous analog signal storage requirement is substituted by discrete digital conversion and parallel processing, eliminating the mechanical/analog memory component while achieving the same functional goal through digital means
2Device complexity
If linear sequential reading is used for distance measurement light, then the measurement process is simplified, but the productivity decreases due to time-consuming sequential processing
Solution Approach 1:
The pixel array is divided into multiple segments, each processed by a dedicated ADC converter. This segmentation enables parallel processing of distance measurement signals from different pixel groups simultaneously, dramatically increasing processing productivity while maintaining systematic organization through the segmented architecture
Solution Approach 2:
The reading process uses periodic clock signals to control the sequential activation of multiple ADC converters. By organizing the parallel processing into periodic cycles with controlled timing, the system achieves high-speed processing while maintaining simple control logic through rhythmic, periodic operation patterns
3Loss of information
If analog memory is implemented in each pixel, then information holding capability is improved, but the manufacturing precision requirements increase due to analog circuit complexity
Solution Approach 1:
Analog memory circuits are completely replaced with digital ADC converters and digital signal processing elements. This substitution eliminates the need for precise analog circuit fabrication, as digital circuits are more tolerant of manufacturing variations and can be manufactured with standard precision while maintaining information holding capability through digital storage
Solution Approach 2:
The system changes the operational parameter from analog signal storage to digital signal conversion. By transforming the signal domain from analog to digital at the point of conversion, the system achieves information holding capability through digital means that are less sensitive to manufacturing precision variations, allowing standard fabrication processes to be used
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 allows for efficient digital signal processing of pixel signals, eliminating the need for a holding unit and enabling effective distance measurement without the complexity of analog memory, thereby improving the device's operational efficiency.
Implementation Method 1
one light receiving unit receiving light input to a pixel for photoelectrical conversion
Data Source
AI summary
The present disclosure relates to a solid state imaging device and an electronic device from which a holding unit for holding information in a pixel can be eliminated. When a charge distribution unit distributes a pixel signal SIG to a first ADC, a pixel signal representing only reflection light is divided for allocation. When the charge distribution unit distributes a pixel signal SIG to a second ADC, a pixel signal representing background light and reflection light (partial) is divided for allocation. When the charge distribution unit distributes a pixel signal SIG to a third ADC, a pixel signal representing background light and reflection light (the rest) is divided for allocation. During a period in which no signal is acquired, a discharge transistor functions as an overflow portion for releasing electrical charge. The present disclosure can be applied to, for example, a solid state imaging device used for an imaging device.