Semiconductor Package Ground Impedance for Noise Isolation
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Solution Overview
Problem
Semiconductor packages face challenges in managing high frequency noise between analog and digital circuit blocks, leading to increased package size and instability due to separate grounds, and noise coupling issues as clock speeds rise.
Innovation Solution
Integrating grounds with higher inductance for analog circuit blocks and lower inductance for digital circuit blocks, using meandering or spiral metal wirings, and capacitors to prevent noise coupling, while maintaining a reduced number of package ground balls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate grounds are used for analog and digital circuit blocks, then noise coupling between analog and digital grounds is reduced, but the number of package ground balls increases and package size increases
Solution Approach 1:
The ground connection is segmented into two distinct impedance paths: an analog ground impedance path and a digital ground impedance path. These paths are separated within the package but converge at the system board level, allowing noise isolation while maintaining a compact package footprint.
Solution Approach 2:
Different impedance characteristics are assigned to different ground paths based on local requirements: the analog ground path uses higher impedance to isolate noise, while the digital ground path uses lower impedance for stable reference. This local differentiation resolves the contradiction between noise isolation and package size.
2Object-affected harmful factors
If separate grounds are used for analog and digital circuit blocks, then noise coupling is reduced, but ground stability decreases and return current path becomes long
Solution Approach 1:
The ground system is segmented into separate analog and digital paths with different impedance characteristics, allowing each path to be optimized for its specific function while maintaining overall system stability through controlled convergence at the board level.
Solution Approach 2:
The impedance parameter of ground paths is changed and differentiated: analog ground paths use higher impedance to block noise, while digital ground paths use lower impedance for stability. This parameter differentiation allows simultaneous achievement of noise isolation and ground stability.
3Area of stationary object
If grounds are integrated for analog and digital circuit blocks, then package size is reduced, but noise coupling between analog and digital grounds occurs
Solution Approach 1:
Within the integrated package structure, the ground network is segmented into distinct analog and digital impedance paths that remain electrically separate until the board level, preventing noise coupling while maintaining compact packaging.
Solution Approach 2:
The package-level ground system merges analog and digital grounds into a single integrated structure, but incorporates internal segmentation through different impedance paths to prevent noise coupling, achieving both compact size and noise isolation.
4Speed
If clock speed of semiconductor devices is increased, then processing performance is improved, but noise generation increases and requires noise removal from package
Solution Approach 1:
The ground system provides locally optimized impedance characteristics for different circuit blocks: higher impedance paths for analog sections to reject high-frequency noise from fast digital switching, and lower impedance paths for digital sections to maintain stable reference during high-speed operation.
Solution Approach 2:
The impedance parameter of ground paths is optimized for different frequency ranges: analog ground paths use higher impedance to attenuate high-frequency noise generated by increased clock speeds, while digital ground paths maintain lower impedance for stable operation at high speeds.
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 approach ensures stable power integrity, reduces package size, and effectively isolates high frequency noise between analog and digital circuit blocks, enhancing system performance.
Implementation Method 1
an inductance of the analog ground impedance may be greater than an inductance of the digital ground impedance
Implementation Method 2
an end portion of the at least one capacitor is connected to the analog circuit block and the other end portion of the at least one capacitor is connected to the integrated ground layer
Data Source
AI summary
A semiconductor package removes power noise by using a ground impedance. The semiconductor package includes an analog circuit block, a digital circuit block, an analog ground impedance structure, a digital ground impedance structure, and an integrated ground. The integrated ground and the analog circuit block are electrically connected via the analog ground impedance structure, and the integrated ground and the digital circuit block are electrically connected via the digital ground impedance structure, and an inductance of the analog ground impedance structure is greater than an inductance of the digital ground impedance structure.