Image Sensor Output Timing to Distribute Peak Current
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Solution Overview
Problem
Conventional CMOS image sensors experience transient peak currents when outputting digital signals, which can lead to voltage drops and affect high-speed circuits like analog-to-digital converters, particularly in high-resolution imaging applications.
Innovation Solution
The image sensor employs multiple analog-to-digital converters and output circuits with independent enable control signals, allowing for staggered output of bit values to distribute peak current, reducing the risk of voltage drops by controlling the timing of enable signals for each pixel row.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If digital signals corresponding to column lines are output to buffers at the same time, then high-speed processing is achieved, but transient peak current occurs causing voltage drop
Solution Approach 1:
The patent segments the simultaneous output operation into multiple sequential output operations. Different pixel rows are divided into groups, and digital signals from different groups are output at different time periods. This segmentation distributes the peak current across multiple time slots while maintaining high-speed processing capability.
Solution Approach 2:
The patent dynamically adjusts the output timing of digital signals from different pixel rows. By controlling output circuits to sequentially output signals from different row groups at different time periods, the system adapts the output schedule to distribute current demand, preventing simultaneous peak current while preserving overall processing speed.
2Productivity
If multiple analog-to-digital converters output bit values simultaneously, then processing throughput is improved, but peak current increases causing voltage drop
Solution Approach 1:
The patent segments the simultaneous output operation into multiple sequential output operations. Different pixel rows are divided into groups, and digital signals from different groups are output at different time periods. This segmentation distributes the peak current across multiple time slots while maintaining high-speed processing capability.
Solution Approach 2:
The patent implements periodic action by outputting digital signals from different pixel row groups in alternating time periods. First pixel rows output in one period, second pixel rows output in the next period, creating a periodic pattern that distributes current demand over time while maintaining continuous high throughput.
Data Source
AI summary
The image sensor includes a first analog-to-digital converter configured to convert a first analog pixel signal output from a first pixel in a row into first digital signals, a second analog-to-digital converter configured to convert a second analog pixel signal output from a second pixel in the row into second digital signals, a first output circuit configured to output a first bit value at a first position in the first digital signals in response to a first enable control signal, and a second output circuit configured to output a second bit value at a second position in the second digital signals in response to a second enable control signal, the second position in the second digital signals corresponding to the first position in the first digital signals, wherein the second enable control signal is activated with a delay from the activation of the first enable control signal.