Parallel Amplification Transistors for High Frame Rate CMOS Imaging
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Solution Overview
Problem
Reducing random noise and maintaining image quality in solid-state imaging devices while achieving high frame rate image capture, which is compromised by decreasing gate length or increasing gate width of amplification transistors.
Innovation Solution
Connecting multiple amplification transistors in parallel and using a selection transistor to output signals to a vertical signal line, with the threshold voltage of the selection transistor set lower than the amplification transistors, and the on-resistance of the load transistor adjusted to minimize noise and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate length L of the amplification transistor is decreased or the gate width W is increased to increase transconductance gm for high frame rate image capture, then the image capture speed is improved, but the random noise of the amplification transistor increases or the saturated signal amount of the pixel decreases, resulting in deteriorated image quality
Solution Approach 1:
The pixel unit is divided into multiple independent photodiodes, each with its own amplification transistor and signal processing path. This segmentation allows each photodiode to operate independently with optimized transistor dimensions, avoiding the noise and saturation issues that would result from increasing the size of a single shared amplification transistor.
Solution Approach 2:
The invention changes the structural parameter of the pixel array by providing multiple photodiodes per pixel unit instead of a single shared photodiode. This parameter change enables high frame rate capture through increased transconductance while maintaining image quality by distributing the signal processing across multiple independent paths, thereby avoiding the trade-off between capture speed and image quality.
2Productivity
If multiple amplification transistors are used to increase transconductance for high frame rate capture, then the image capture speed is improved, but the device complexity increases
Solution Approach 1:
Multiple photodiodes and their associated amplification transistors are merged into a single pixel unit that shares common control signals and readout pathways. This merging approach increases transconductance for high frame rate capture while managing device complexity by consolidating control and output functions at the pixel unit level.
Solution Approach 2:
The pixel unit structure provides multi-functionality by enabling both high frame rate image capture through multiple amplification transistors and maintaining compatibility with existing readout architectures. The universal pixel unit design can handle different capture modes and frame rates without requiring fundamentally different structural approaches.
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
Enables high frame rate image capture without deteriorating image quality by increasing transconductance while controlling noise and linearity, thus allowing for effective signal processing and output.
Implementation Method 1
one or more photoelectric conversion units
Data Source
AI summary
The present technology relates to a solid-state imaging device and an electronic apparatus that realize a high frame rate image capture without deteriorating an image quality. A floating diffusion holds a charge accumulated on one or more photoelectric conversion units. A plurality of amplification transistors read out a signal corresponding to the charge held by the floating diffusion. The signal read out by the amplification transistor is output to a vertical signal line. The plurality of amplification transistors are connected in parallel. The present technology is applicable to a CMOS image sensor, for example.