Integrated Faraday Shield for Mixed-Signal IC EMI Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional RF shielding methods, such as metal cans and package-level plating, are costly, space-consuming, and ineffective in protecting integrated circuits from both radiated and substrate-coupled electromagnetic interference (EMI), particularly in mixed signal RF ICs, where substrate noise can degrade analog circuitry performance.
Innovation Solution
Integrated Faraday shields formed during wafer fabrication using through substrate vias (TSVs) arranged in a cage-like pattern to surround sensitive circuitry, electrically coupled to conducting members on the substrate, providing protection from both radiated and substrate-coupled EMI, and incorporating on-chip voltage regulators for a regulated power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional metal cans are used for RF shielding, then radiated EMI is reduced, but device complexity and space requirements increase
Solution Approach 1:
The patent merges the RF shielding function with the IC substrate itself by integrating Faraday shields directly into the substrate layers. Multiple shielding layers are combined within the substrate structure, eliminating the need for separate external metal cans while maintaining EMI protection functionality.
Solution Approach 2:
The patent transitions from three-dimensional external metal can shielding to two-dimensional planar Faraday shield patterns integrated within the substrate layers. This dimensional change allows shielding to be incorporated into the substrate plane without adding vertical space requirements.
2Object-affected harmful factors
If external metal cans are used for RF shielding, then radiated EMI is reduced, but manufacturing cost and time increase
Solution Approach 1:
The shielding structure is merged with the standard IC fabrication process, allowing Faraday shields to be created using existing photolithography and deposition techniques. This integration eliminates separate manufacturing steps and reduces overall production cost and time.
Solution Approach 2:
The IC substrate serves multiple functions: it provides mechanical support, electrical interconnection, and EMI shielding. This multi-functionality eliminates the need for dedicated shielding components and simplifies the manufacturing process.
3Object-affected harmful factors
If larger spacings between digital logic and RF circuitry are used, then substrate noise coupling is reduced, but device area increases
Solution Approach 1:
Faraday shields serve as intermediary structures between digital logic and RF circuitry, providing electromagnetic isolation without requiring large physical spacings. These shield patterns act as mediators that block noise transmission while allowing compact circuit placement.
Solution Approach 2:
The patent uses composite substrate structures with integrated Faraday shield layers, combining conductive shielding materials with the substrate material. This composite approach provides effective noise isolation in a compact footprint by creating electromagnetic barrier layers within the substrate itself.
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
The integrated Faraday shields effectively decouple sensitive circuitry from noisy digital logic, reducing substrate noise and protecting against high-frequency EMI, allowing for on-chip isolation and efficient power management, thereby enhancing the performance of mixed signal ICs.
Implementation Method 1
integrated Faraday shields formed during the wafer fabrication process that comprise through substrate vias (TSVs) arranged in a cage-like pattern to surround or 'cage' the EMI sensitive circuitry
Implementation Method 2
The TSVs are electrically coupled to electrically conducting members on the top and bottom surface of same substrate (e.g., silicon) to form an integrated Faraday shield
Data Source
AI summary
An integrated circuit (IC) includes a substrate having a top semiconductor surface and a bottom surface, and integrated circuitry including an analog subcircuit and at least one digital subcircuit formed on the top semiconductor surface. A plurality of through substrate vias (TSVs) extend through the substrate. At least one integrated Faraday shield includes a top and a bottom electrically conducting member that are coupled by the TSVs which surround the analog subcircuit and/or the digital subcircuit. At least one voltage regulator supplies a regulated power supply voltage that is coupled to the integrated Faraday shield that surrounds the analog subcircuit.