Image Sensor Data Transmission Circuit EMI Reduction
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Solution Overview
Problem
The proximity of additional antennae to image sensors in mobile devices can lead to electromagnetic interference (EMI) due to switching operations, which is undesirable and affects data transmission efficiency.
Innovation Solution
A data transmission circuit with a series of banks and latches is used, where image data is propagated sequentially through each bank, controlled by a delayed common clock signal, reducing peak current and concurrent switching events to minimize EMI and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is transmitted using conventional parallel switching operations in image sensors, then data transmission speed is improved, but electromagnetic interference increases
Solution Approach 1:
The patent segments the data transmission process by dividing the pixel array into multiple banks and using sequential row-by-row readout instead of simultaneous parallel readout. This segmentation distributes the switching operations over time, reducing peak current and electromagnetic interference while maintaining data transmission functionality.
Solution Approach 2:
The patent implements periodic action by using a shifted clock signal to sequentially enable different banks at different time periods. Each bank is activated in sequence rather than simultaneously, creating a periodic pattern of switching operations that reduces electromagnetic interference while maintaining continuous data flow.
2Device complexity
If multiple antennae are placed close to image sensors for wireless transmission, then device integration is improved, but electromagnetic interference from sensor switching operations increases
Solution Approach 1:
By segmenting the pixel array into multiple banks with sequential readout, the patent reduces the peak switching current generated by the image sensor. This allows the sensor to be placed closer to wireless antennae without causing harmful electromagnetic interference, thereby enabling better device integration.
Solution Approach 2:
The periodic activation of different banks using shifted clock signals distributes switching operations over time, reducing the electromagnetic noise floor. This enables closer placement of wireless antennae to the image sensor while maintaining signal integrity and reducing interference.
3Productivity
If parallel switching operations are used for fast data readout, then productivity is improved, but power consumption increases
Solution Approach 1:
The patent segments the readout operation into sequential bank-by-bank processing, which reduces peak power consumption by distributing switching events over time. Multiple banks can be processed in succession, maintaining productivity while reducing the instantaneous power draw associated with simultaneous parallel switching.
Solution Approach 2:
By using periodic clock signals to sequentially activate different banks, the patent reduces peak power consumption while maintaining continuous data flow. The periodic nature of the switching operations allows for more efficient power management compared to sustained parallel switching.
Data Source
AI summary
Methods and apparatuses for data transmission in an image sensor are disclosed herein. An example data transmission circuit may include a plurality of transmission banks coupled in series with a first one of the plurality of transmission banks coupled to function logic, where each of the plurality of transmission banks are coupled to provide image data to a subsequent transmission bank in a direction toward the function logic in response to a clock signal, a plurality of delays coupled in series, wherein each of the plurality of delays is associated with and coupled to a respective transmission bank of the plurality of transmission banks, and wherein the clock signal is received by each of the plurality of transmission banks after being delayed by a respective number of delays of the plurality of delays in relation to the function logic.