Column ADC Ripple Counter Layout for Stable High-Speed Image Sensing
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Solution Overview
Problem
Conventional CMOS image sensors face challenges in reducing chip size, preventing count value changes during operation switching, and increasing data transmission speed due to the size and complexity of up/down ripple counters and memory devices.
Innovation Solution
The implementation of a CMOS image sensor with a controller generating specific control signals to manage up/down ripple counters and memory chains, utilizing latches and switch blocks to prevent count value changes and enhance data transmission speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single ADC operating at high speed is used to convert analog pixel signals, then conversion speed is improved, but power consumption increases
Solution Approach 1:
The patent divides the single high-speed ADC into multiple column ADCs, each operating at lower speed but collectively achieving the required conversion throughput. Each column ADC processes signals from a specific column of pixels, segmenting the overall conversion task into parallel sub-tasks that consume less power individually while maintaining system-level productivity.
2Use of energy by moving object
If multiple column ADCs are used to reduce power consumption, then power consumption is reduced, but chip size increases
Solution Approach 1:
The patent merges the up/down ripple counter and memory device into an integrated ADC module for each column. This consolidation eliminates the need for separate counter and memory components, reducing the overall chip area while maintaining the power-saving benefits of multiple column ADCs. The integrated design shares common circuitry and resources across the multiple ADCs.
3Adaptability or versatility
If up/down ripple counters are used for counting operations, then counting functionality is achieved, but count values change during operation switching
Solution Approach 1:
The patent freezes the count value in advance before switching between up-counting and down-counting operations. By latching the current count value prior to operation switching, the system prevents any transient changes or instability that would occur during the transition, ensuring reliable and stable count values are maintained throughout operation switching.
4Quantity of substance
If conventional memory devices are used to store count values, then data storage is achieved, but data transmission speed is limited
Solution Approach 1:
The patent introduces a data bus as an intermediary between the integrated ADC module and the external interface. This dedicated data transmission pathway enables high-speed transfer of digital signals and count values without being bottlenecked by conventional memory device read/write speeds, effectively decoupling storage capacity from transmission speed limitations.
Data Source
AI summary
An example embodiment of an image sensor may include a controller and a plurality of up/down ripple counters. The controller may generate a first control signal and a second control signal. Each of the up/down ripple counters may perform a stop operation or a count operation in response to a corresponding one of a plurality of operation control signals generated based on at least in part on the first control signal. The count operation may be an up-count operation or a down-count operation based on the second control signal. The image sensor may also include a plurality of memory chains. Each of the memory chains may receive a count value output from the up/down counters and may shift the received count value in response to a third control signal and a fourth control signal output from the controller.