EMI Evaluation System for Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cell phone manufacturers face challenges in understanding and mitigating radio-frequency emissions (RFR) from electronic components, particularly image sensors, which cause electromagnetic interference (EMI) with digital radio transceivers, often identified late in the design process, necessitating early characterization of RFR magnitude and frequency to improve phone performance and reduce EMI.
Innovation Solution
A test apparatus and method involving an image sensor PCB with decoupling capacitors and an image processor PCB, where the image processor IC is outside a shielding box and decoupling capacitors are within, allowing for measurement of RFR coupled to a cell phone antenna, with the system configured to exclude ambient radiation and accurately quantify RFR from image sensors at full operating speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image sensor IC is operated at full speed to characterize RFR, then measurement accuracy is improved, but radiated harmonics increase sharply
Solution Approach 1:
A shielded compartment is introduced as an intermediary between the image sensor IC and the measurement antenna. The shielded compartment contains the image sensor IC and decoupling capacitors, while the antenna is positioned outside the shield. This mediator allows the measurement of RFR from the sensor at full operating speed while blocking the direct path of radiated harmonics to the antenna, thus resolving the contradiction between measurement accuracy and harmonic reduction.
2Object-affected harmful factors
If decoupling capacitors are placed close to image sensor IC, then EMI reduction is improved, but layout complexity increases
Solution Approach 1:
The PCB is segmented into distinct functional zones: a shielded compartment containing the image sensor IC and its decoupling capacitors, and an unshielded area containing the antenna and other components. This segmentation allows decoupling capacitors to be placed optimally close to the IC for EMI reduction while organizing the overall layout to manage complexity through clear spatial separation of functions.
3Object-generated harmful factors
If shielding is added to reduce RFR coupling, then EMI is reduced, but device complexity and cost increase
Solution Approach 1:
Shielding is applied locally only to the image sensor IC and its immediate decoupling capacitors within a compact compartment, rather than implementing full-device shielding. This localized approach reduces RFR coupling at the critical source while minimizing the overall complexity and cost of the shielding structure.
4Productivity
If EMI issues are identified late in design process, then manufacturing progress is maintained, but solution implementation time increases
Solution Approach 1:
The shielded compartment design and decoupling capacitor placement are implemented during the preliminary PCB layout stage, before final assembly and testing. This preliminary action allows EMI mitigation measures to be built into the design from the beginning, enabling early identification and resolution of potential RFR issues rather than addressing them late in the development process.
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
Enables early identification and reduction of EMI issues by quantifying RFR from image sensors, facilitating design improvements in cell phones, reducing the likelihood of signal interference and enhancing communication range at low power.
Implementation Method 1
the image sensor IC and antenna being within the shielded compartment
Implementation Method 2
image sensor decoupling capacitors disposed on a second side, the image sensor PCB disposed within a shielding box
Data Source
AI summary
An apparatus configured to measure electromagnetic radiation coupled from an image sensor integrated circuit (IC) to a nearby cell phone antenna has an image sensor PCB with the image sensor IC on a first side and image sensor decoupling capacitors disposed on a second side, the image sensor PCB disposed within a shielding box. The apparatus also has an image processor PCB with an image processor IC on a first side and at least one image processor decoupling capacitors, the image processor IC electrically coupled to the image sensor IC. The image processor IC is located outside the shielding box, and the at least one image processor decoupling capacitor is within the shielding box. In embodiments, the decoupling capacitors are shielded with separate, additional, metal covers.