I/O Cell Library Layout for Shared-Pad Multi-Voltage Protection
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Solution Overview
Problem
Existing I/O circuit designs using standard cell libraries face challenges in creating a protection system when a single pad is shared between digital and analog circuits operating on different supply voltages, leading to increased circuit area and complexity.
Innovation Solution
The I/O circuit is formed by combining standard cells with a novel configuration where a second power line is isolated to connect a protection element to a different supply voltage, allowing the protection element and analog circuit to operate on a common supply voltage without requiring separate protection elements, thus simplifying the power supply system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single pad is shared between digital and analog circuits with different supply voltages, then pad utilization is improved, but circuit complexity increases due to the need for multiple protection elements
Solution Approach 1:
The protection element is designed to handle multiple voltage domains (first supply voltage for digital circuit and second supply voltage for analog circuit) through a single unified structure. The power line configuration allows the same protection element to protect against electrostatic discharge from both voltage domains, eliminating the need for separate protection elements for each voltage domain.
Solution Approach 2:
Multiple protection functions for different voltage domains are merged into a single protection element. The power line is configured to connect the protection element to both the first supply voltage (digital) and second supply voltage (analog), combining what would traditionally require separate protection circuits into one integrated solution.
2Reliability
If separate protection elements are used for digital and analog circuits, then protection reliability is improved, but circuit area increases
Solution Approach 1:
The patent merges multiple protection functions into a single protection element that serves both digital and analog circuits. By configuring the power line to connect the protection element to multiple supply voltages, the design achieves comprehensive protection while occupying only one protection element area instead of multiple separate protection elements.
3Adaptability or versatility
If multiple power lines are used to connect protection elements to different supply voltages, then power supply flexibility is improved, but wiring complexity increases
Solution Approach 1:
The power line is designed as a multi-functional conductor that connects the protection element to multiple supply voltage domains. This unified power line configuration provides flexible power supply connections for both digital and analog circuits while avoiding the need for separate dedicated power lines for each voltage domain, thereby reducing wiring complexity.
Data Source
AI summary
For example, an I/O circuit is formed by freely combining a plurality of kinds of standard cells included in a cell library. The plurality of kinds of standard cells include at least first standard cells and a second standard cell. The first standard cells include first protection elements and a first power line formed in a region over the first protection elements to conduct to the first protection elements. The second standard cell includes a second protection element formed in a layout identical with that of the first protection elements, and a second power line formed in a region over the second protection element to conduct to the second protection element while being isolated from the first power line.