Column ADC Layout for Fine-Pitch Photoelectric Conversion
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Solution Overview
Problem
Existing MOS-type photoelectric conversion apparatuses face challenges in increasing signal output speed without increasing the element arrangement pitch for pixel columns, particularly when finer pixel arrangements are required, which can lead to deterioration of the apparatus's properties due to the need for more wiring layers.
Innovation Solution
The arrangement of AD converter components on a semiconductor substrate is optimized by placing the comparator circuit unit in a first region, the arithmetic operation amplifying circuit unit in a second region, and the DA converted circuit unit in a third region, allowing for a shorter signal path and reduced wiring density, enabling a smaller pixel arrangement pitch without increasing the number of wiring layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If AD converters are provided for each pixel column to increase signal output speed, then productivity is improved, but device complexity increases due to additional wiring layers
Solution Approach 1:
The patent applies dimensional reorganization by arranging circuit units in distinct spatial regions (first, second, and third regions) rather than following linear signal flow. This spatial redistribution reduces wiring layer complexity while maintaining the parallel AD converter architecture needed for high-speed output
Solution Approach 2:
The AD converter is segmented into three independent circuit units (comparator, arithmetic operation amplifying circuit, and DA converted circuit) positioned in separate regions. This segmentation allows each unit to be optimized independently and reduces interconnections, thereby decreasing overall wiring complexity while preserving functional performance
2Ease of manufacture
If elements are arranged following signal flow in AD converter, then ease of manufacture is improved, but pixel arrangement pitch increases
Solution Approach 1:
The patent breaks the conventional linear arrangement by distributing circuit units across multiple spatial regions rather than sequencing them along signal flow. This dimensional reorganization enables finer pixel pitch while maintaining manufacturing simplicity through standardized regional placement
Solution Approach 2:
Each circuit unit is assigned to a specific region with optimized local characteristics. The comparator unit in the first region, arithmetic operation amplifying circuit in the second region, and DA converted circuit in the third region can each be manufactured with local optimizations, achieving both ease of manufacture and reduced pitch
Data Source
AI summary
Providing a configuration that, when an AD converter is provided for each of pixel columns, enables each of the elements to be arranged without increasing the element arrangement pitch. A photoelectric conversion apparatus according to the present invention includes a plurality of AD converters. The AD converter includes: an arithmetic operation amplifying circuit unit, a comparator circuit unit for comparing, with a reference signal, an output from the arithmetic operation amplifying circuit unit; a DA converted circuit unit for DA converting a signal based on a signal from the comparator circuit unit; and a sampling and holding unit arranged at an input section of the arithmetic operation amplifying circuit unit. The DA converted circuit unit is arranged between the comparator circuit unit and the arithmetic operation amplifying circuit unit.