Lookup-Table Sigma-Delta ADC Filter for Lower Peak Power
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Solution Overview
Problem
The power consumption of sigma-delta analog-to-digital converters (ADCs) in image sensors increases with image resolution, leading to higher battery drain and heat generation, which degrades noise performance and reduces operating time in mobile devices.
Innovation Solution
Implementing a sigma-delta modulator with an ADC filter that stores partial sums in lookup tables, allowing for efficient retrieval and addition of these sums to calculate the output, thereby reducing peak power consumption by partitioning the summation process and using lookup tables to minimize the number of necessary additions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels in the image sensor is increased to improve image resolution, then the image quality is improved, but the power consumption of the ADCs increases
Solution Approach 1:
The patent divides the image sensor into multiple blocks, with each block having its own shared ADC. This segmentation allows the system to handle high-resolution images while reducing the power consumption per ADC by sharing resources within each block, thus resolving the contradiction between maintaining high image resolution and reducing overall power consumption.
2Productivity
If the number of ADCs is increased to handle more pixels, then the image processing capability is improved, but the power consumption and heat generation increase
Solution Approach 1:
The patent merges multiple photoelectric conversion devices into shared ADC blocks, where multiple pixels share a common ADC resource. This merging approach maintains the image processing capability for high-resolution sensors while reducing the total number of ADCs required, thereby lowering power consumption and heat generation.
3Duration of action of moving object
If the power consumption is reduced to improve battery life, then the operating time is improved, but the temperature control becomes more challenging
Solution Approach 1:
By segmenting the image sensor into multiple blocks with shared ADCs, the patent reduces the power consumption per block, which extends battery life and operating time. The segmented architecture also distributes heat generation across multiple smaller blocks rather than concentrating it in a single high-power ADC, making temperature control more manageable.
4Productivity
If the number of ADCs is increased to handle higher resolution, then the image processing capability is improved, but the area usage increases
Solution Approach 1:
The patent merges multiple photoelectric conversion devices into shared ADC blocks, reducing the total number of ADCs required. This merging strategy maintains the image processing capability for high-resolution sensors while significantly reducing the silicon area occupied by ADC circuitry, thus resolving the contradiction between processing capability and area usage.
Data Source
AI summary
An analog-to-digital converter comprises a sigma-delta modulator; and an ADC filter configured to store a plurality of partial sums as respective entries in a plurality of lookup tables, retrieve at least one of the plurality of partial sums based on an output of the sigma-delta modulator, and calculate a filter output by adding retrieved ones of the plurality of partial sums together.