Column Readout Circuit for Noise-Free Dual-Gain Image Sensors
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Solution Overview
Problem
The existing solid-state imaging devices face a noise gap at the connection point between low conversion gain and high conversion gain data, leading to increased power consumption and circuit areas, which affects image quality and dynamic range.
Innovation Solution
A solid-state imaging device with a column signal processing part that includes an amplifier with inverting and non-inverting input terminals, featuring multiple input and output switches and sampling capacitors, allowing for simultaneous first and second conversion gain mode readings to combine read-out signals from pixels, thereby eliminating the noise gap and enhancing dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple conversion gain modes are used to extend dynamic range, then the dynamic range is improved, but a noise gap appears at the connection point between different gain data
Solution Approach 1:
The patent merges low conversion gain data and high conversion gain data through a unified signal processing pipeline. The reading circuit combines signals from multiple pixels that have been read out in different conversion gain modes, processing them together to eliminate the noise gap that would otherwise appear at their connection point.
Solution Approach 2:
The patent introduces a unified reading circuit as an intermediary that processes both low conversion gain and high conversion gain signals. This intermediary circuit performs correlated double sampling and signal combination operations that bridge the two different gain modes, preventing the noise gap from manifesting in the final output.
2Illumination intensity
If separate processing circuits are used for different conversion gain modes, then the dynamic range is improved, but the circuit area increases
Solution Approach 1:
The patent designs a universal reading circuit that can process signals from multiple pixels read out in different conversion gain modes. This multi-functional circuit performs correlated double sampling, signal amplification, and combination operations for both low and high conversion gain signals, eliminating the need for separate dedicated processing circuits for each gain mode.
Solution Approach 2:
The patent combines the signal processing functions for different conversion gain modes into a single unified circuit. By merging the processing paths and using shared components such as sampling capacitors, amplifiers, and correlation circuits, the total circuit area is reduced while maintaining the ability to handle multiple gain modes.
3Illumination intensity
If separate processing circuits are used for different conversion gain modes, then the dynamic range is improved, but power consumption increases
Solution Approach 1:
The patent creates a universal reading circuit that handles both low and high conversion gain signals through shared processing stages. This multi-functional approach allows the same circuit components to be reused for different signal types, reducing the total number of active elements and thereby lowering overall power consumption compared to having separate dedicated circuits for each gain mode.
Solution Approach 2:
The patent merges the processing of different conversion gain signals into a unified pipeline, combining amplification, sampling, and correlation operations in shared circuit blocks. This consolidation reduces redundant power consumption that would occur in separate processing circuits, while still maintaining the extended dynamic range capability.
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 solution effectively removes the noise gap, suppresses power consumption and circuit area increases, and provides a wide dynamic range, resulting in high image quality.
Implementation Method 1
a photodiode (a photoelectric conversion element) and a floating diffusion (FD) amplifier
Data Source
Figure 1
Figure 2(A)~2(D)
Figure 3
AI summary
One object is to provide a solid-state imaging device, a method for driving a solid-state imaging device, and an electronic apparatus capable of removing a noise gap at a connection point between the low conversion gain data and the high conversion gain data, suppressing increase of power consumption and circuit areas, providing a wide dynamic range, and thus achieving high image quality. An amplifying part for amplifying a plurality of pixel signals read out from a pixel includes an amplifier. The amplifier includes an inverting input terminal and a noninverting input terminal. The inverting input terminal includes a first inverting input channel and a second inverting input channel. The first inverting input channel is connected to a second node, and the second inverting input channel is connected to a third node. A capacitance of a second sampling capacitor is 8C, and a capacitance of a first sampling capacitor is C.