Solid-State Imaging Column Circuit Noise Reduction
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Solution Overview
Problem
Conventional solid-state imaging devices struggle to completely remove fixed pattern noise due to variations in column circuits, which deteriorate image quality despite noise removal processes like correlated double sampling.
Innovation Solution
The method involves an amplification and selection circuit that performs sampling, holding, and amplification of differential signals from column pixel and reset signals in parallel, using feedback capacitors to alternate and amplify the signals, and strategically connecting column circuits to minimize wiring length for improved noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional column circuits with separate transistors for sampling optical signal and reset signal are used, then correlated double sampling can be performed, but fixed pattern noise cannot be completely removed due to variations in column circuits
Solution Approach 1:
The patent merges the control of sampling switches into a single shared transistor that controls both the optical signal sampling switch and the reset signal sampling switch. This unified control mechanism ensures that both sampling operations are synchronized and experience identical variations, allowing the variations to be canceled out during the differential amplification process, thereby completely removing fixed pattern noise.
Solution Approach 2:
The patent changes the control parameter from separate transistor controls to a shared transistor control, where the same control signal is applied to both sampling switches. This parameter change ensures that any variations in the control signal affect both channels equally, making the variations common-mode signals that can be rejected by the differential amplifier, thus achieving complete fixed pattern noise removal.
2Measurement precision
If multiple sampling operations are performed sequentially in column circuits, then noise removal can be achieved, but processing time increases and productivity decreases
Solution Approach 1:
The patent employs periodic action by alternating between sampling the optical signal and sampling the reset signal in different column circuits during the same time period. While one column circuit samples the optical signal, another column circuit samples the reset signal, and vice versa. This periodic alternation allows both sampling operations to be completed in parallel over time, maintaining high processing speed while achieving complete noise removal through the subsequent differential amplification.
Data Source
AI summary
There is provided a method of driving a solid-state imaging device, the solid-state imaging device including a plurality of column circuits which are arranged for each column of pixels and an amplification and selection circuit configured to amplify a differential signal based on a column pixel signal and a column reset signal, the method including causing the amplification and selection circuit to perform at least two operations among a first operation of sampling the column pixel signal, a second operation of sampling the column reset signal, and a third operation of output the amplified differential signal in parallel in the same period; and causing components connected to different horizontal signal lines to perform operations corresponding to the first to third operation in that order, and causing the components to perform different operations in parallel in the same period with respect to the first to third operations.