Dual-Current Ramp Voltage Circuit for CMOS Image Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image sensing devices, particularly CMOS image sensors, face challenges in optimizing the generation of ramp voltages for efficient image capture, as existing circuit structures are not adequately designed to integrate coarse and fine ramp currents effectively, leading to suboptimal image signal processing.
Innovation Solution
The proposed image sensing device incorporates a ramp voltage generator with optimized circuit structures, including coarse and fine current generation circuits and a current-to-voltage conversion circuit, which generate and manage coarse and fine ramp currents to produce a resultant ramp voltage, enhancing the integration of high and low voltage sources and improving image signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ramp voltage generator circuit is used, then the device complexity is reduced, but the manufacturing precision of ramp voltage generation deteriorates
Solution Approach 1:
The ramp voltage generator is segmented into two independent current generation circuits: a coarse current generation circuit and a fine current generation circuit. Each circuit independently generates current with different precision levels, which are then combined to achieve high overall precision without requiring a single complex circuit
Solution Approach 2:
The coarse current and fine current from the two separate circuits are merged through a current combining circuit to form the total ramp current. This merging allows the system to achieve high precision by combining the outputs of simpler, specialized circuits rather than using one complex circuit
2Manufacturing precision
If coarse and fine current generation circuits are integrated, then the ramp voltage generation precision is improved, but the device complexity increases
Solution Approach 1:
The system is divided into specialized coarse and fine current generation circuits, each optimized for its specific function. This segmentation allows each circuit to be simpler in design while achieving high overall precision through their combination
Solution Approach 2:
The current combining circuit serves as a universal interface that accepts inputs from both coarse and fine current generation circuits, merging them into a single ramp current output. This multi-functional component handles both current types without requiring separate processing paths
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 enables the generation of optimized ramp voltages, improving image sensing capabilities by effectively integrating coarse and fine ramp currents, thereby enhancing the image signal processing and reducing the complexity and area occupancy of the ramp voltage generator.
Implementation Method 1
a current-to-voltage conversion circuit suitable for generating a ramp voltage corresponding to a resultant current of the coarse ramp current and the fine ramp current
Data Source
AI summary
An image sensing device includes a coarse current generation circuit suitable for generating a coarse ramp current adjusted to a coarse level for a single ramp period, a fine current generation circuit suitable for generating a fine ramp current adjusted to a fine level for the single ramp period, and a current-to-voltage conversion circuit suitable for generating a ramp voltage corresponding to a resultant current of the coarse ramp current and the fine ramp current for the single ramp period.