Separate Analog and Digital Ground Layers for Noise Isolation
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Solution Overview
Problem
Noise from digital integrated circuits can destabilize the operation of analog integrated circuits due to shared ground layers, particularly high-frequency noise from digital circuits affecting analog circuits.
Innovation Solution
A semiconductor device with separate analog and digital ground layers and terminals, along with a floating digital ground layer, is designed to isolate noise, using a redistribution layer and power supply electrode configuration to prevent noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared ground layer is used for both analog and digital integrated circuits, then the device complexity is reduced and manufacturing is simplified, but noise from digital circuits destabilizes analog circuit operation
Solution Approach 1:
The ground layer is segmented into separate analog ground layers and digital ground layers. The analog ground layer is dedicated to analog integrated circuits while the digital ground layer serves digital integrated circuits, preventing noise coupling between the two types of circuits through ground path interference.
Solution Approach 2:
A via structure serves as an intermediary connection element that selectively connects power supply electrodes to ground layers. The via configuration allows certain power supply electrodes to connect to analog ground layers while others connect to digital ground layers, mediating the separation function between analog and digital grounds.
2Adaptability or versatility
If digital and analog circuits are integrated on the same substrate, then device functionality and versatility are improved, but noise interference between circuits increases
Solution Approach 1:
Different regions of the device are assigned different ground layer configurations tailored to their specific needs. Analog circuit regions are connected to analog ground layers with appropriate via structures, while digital circuit regions are connected to digital ground layers, providing locally optimized noise immunity for each circuit type.
Solution Approach 2:
The ground system is segmented into functionally distinct analog and digital ground layers, allowing simultaneous integration of analog and digital circuits on the same substrate while maintaining electrical separation to prevent noise interference between the two circuit types.
Data Source
AI summary
A semiconductor device includes an analog integrated circuit and a digital integrated circuit provided on a major surface of a substrate. An analog ground terminal is provided for the analog integrated circuit, and digital ground terminals are provided for the digital integrated circuit. An analog ground layer is stacked on the substrate so as to face the analog integrated circuit, and digital ground layers are stacked on the substrate so as to face the digital integrated circuit. The analog ground terminal is connected to the analog ground layer, and the digital ground terminals are connected to the digital ground layers, respectively.