Analog Circuit Noise Isolation Using Segmented Resistive Capacitive Regions
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Solution Overview
Problem
Conventional semiconductor integrated circuit devices face challenges in reducing chip size while effectively suppressing noise interference between digital and analog circuits, leading to increased chip area due to required separation distances and complex noise countermeasure implementations.
Innovation Solution
The semiconductor integrated circuit device separates digital and analog circuits by a shorter distance by arranging capacitive and resistive elements adjacent to the digital circuit and active elements separately, with guard bands to attenuate noise, thereby reducing chip area without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the separation distance between digital circuit region and analog circuit region is increased to suppress noise mixing, then noise suppression is improved, but chip area increases considerably
Solution Approach 1:
The analog circuit region is segmented into active element region and resistive/capacitive element region, with the latter placed adjacent to the digital circuit region to act as a noise buffer zone. This segmentation allows noise suppression without requiring large separation distances.
Solution Approach 2:
Resistive and capacitive elements are introduced as intermediary components between the digital and analog active elements. These elements form RC low-pass filters that attenuate high-frequency noise from the digital circuit before it reaches the sensitive analog active elements.
2Object-affected harmful factors
If special processes are used to form low-resistance wells to suppress noise, then noise suppression is improved, but manufacturing complexity increases
Solution Approach 1:
The invention uses standard resistive and capacitive elements that can be formed using conventional semiconductor fabrication processes, avoiding the need for expensive special processes like low-resistance well formation. These passive elements serve as effective noise filters without adding manufacturing complexity.
3Object-affected harmful factors
If guard ring regions are provided to surround digital circuit region, then noise suppression is improved, but chip area increases by the area required for guard rings
Solution Approach 1:
The noise suppression function is merged with the functional elements of the analog circuit by using resistive and capacitive elements that are part of the analog circuit's signal processing path. This eliminates the need for separate guard ring structures.
Solution Approach 2:
Noise suppression is implemented locally at specific critical points within the analog circuit region rather than surrounding the entire digital circuit region with guard rings. The resistive and capacitive elements are strategically placed only where needed to filter noise before it reaches sensitive analog elements.
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
This configuration allows for a shorter separation distance between digital and analog circuits, effectively suppressing noise and minimizing the increase in chip area, while maintaining noise attenuation through thick element isolation layers and wide capacitive and resistive element regions.
Implementation Method 1
the resistivity of the semiconductor substrate is 1000 times that of the first well or higher
Implementation Method 2
a thick element isolation layer is used to effectively suppress the mixing of noise
Data Source
AI summary
In a semiconductor integrated circuit device including a digital circuit region in which a digital circuit is formed, and an analog circuit region in which an analog circuit is formed, the analog circuit region is separated into an active element region in which an active element of the analog circuit is formed, and a resistive and capacitive element region in which a resistor or a capacitor of the analog circuit is formed, the resistive and capacitive element region is arranged in a region adjacent to the digital circuit region, and the active element region is arranged in a region separated from the digital circuit region.