Solid-State Imaging Pixel Circuit With On-Pixel Signal Amplification
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Solution Overview
Problem
In existing solid-state imaging devices, the separation of pixels and analog-to-digital converters on different substrates leads to longer wiring, which increases noise susceptibility of weak analog pixel signals during transmission.
Innovation Solution
Incorporating a pixel circuit with a first transistor for signal amplification, a second transistor for reference signal input, and a third transistor for bias current output within the pixel circuit, allowing for signal processing and noise reduction within the pixel circuit itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pixels and analog-to-digital converter are arranged on different substrates, then device integration is achieved, but wiring length increases and noise susceptibility worsens
Solution Approach 1:
The patent merges the pixel circuit functions (photoelectric conversion, signal amplification, and analog-to-digital conversion) into a single integrated pixel structure. The pixel circuit includes a photoelectric converter, a first transistor for signal amplification, a second transistor for reference signal input, and a third transistor for bias current output, all arranged within the pixel region on the same substrate. This integration eliminates the need for long inter-substrate wiring and reduces noise susceptibility by keeping the weak analog signals confined to a small area.
2Object-affected harmful factors
If wiring length is reduced, then noise influence is reduced, but device integration is compromised
Solution Approach 1:
The patent combines multiple functional blocks (photoelectric converter, signal amplification circuit with first transistor, reference signal input circuit with second transistor, and bias current output circuit with third transistor) into a single integrated pixel circuit on one substrate. This merging approach reduces wiring length to minimum necessary connections while maintaining full device integration, thereby reducing noise influence on the weak analog pixel signals.
Solution Approach 2:
The patent utilizes vertical stacking and three-dimensional arrangement of circuit components within the pixel region to accommodate multiple functional blocks without increasing planar wiring length. By organizing the photoelectric converter, transistors, and associated circuits in a compact vertical configuration, the design achieves high integration density while keeping signal paths short and minimizing noise exposure.
3Reliability
If signal amplification is performed early in the pixel circuit, then signal integrity is improved, but circuit complexity increases
Solution Approach 1:
The pixel circuit is segmented into distinct functional modules: a photoelectric converter for light detection, a first transistor for signal amplification, a second transistor for reference signal input, and a third transistor for bias current output. Each module performs a specific function and is clearly defined within the pixel circuit. This segmentation allows for systematic design and optimization of each module while maintaining overall signal integrity through early amplification of the weak pixel signal.
Solution Approach 2:
The pixel circuit employs a multi-functional design where the same substrate and interconnect structure support multiple functions: photoelectric conversion, signal amplification, reference signal input, and bias current supply. The first, second, and third transistors work together in a coordinated manner to achieve both signal integrity improvement through early amplification and controlled circuit complexity through shared structural elements.
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 reduces noise interference by shortening the routing wiring and enabling effective signal amplification and conversion within the pixel circuit, enhancing signal integrity.
Implementation Method 1
a pixel signal being generated by a photoelectric converter performing photoelectric conversion on light that has entered a pixel
Data Source
AI summary
A solid-state imaging element (1) includes a pixel circuit (20) in which a first transistor (26) that amplifies a pixel signal is arranged, the pixel signal being generated by a photoelectric converter performing photoelectric conversion on light that has entered a pixel. The pixel circuit (20) includes a second transistor (27) into which a reference signal is input from a reference signal generator, and a third transistor (28) that outputs bias current to the first transistor (26) and the second transistor (27).