Multiple-Port SRAM Cell Layout for Simultaneous Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor integrated circuits (ICs) become smaller and more complex, the layout of memory cells, bit lines, and word lines in multiple-port SRAM devices affects their performance, necessitating an efficient design that allows for simultaneous access to multiple memory cells during a single clock cycle while maintaining optimal layout and performance.
Innovation Solution
The design incorporates a multiple-port static random access memory (SRAM) cell with a storage circuit, write port circuit, and read port circuits, utilizing a specific arrangement of transistors and conductive lines across multiple metal layers to enable simultaneous access to data nodes through different access ports, with a focus on optimizing the ratio of cell width to cell height for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple-port memory cells are used to enable simultaneous access to multiple memory cells during a single clock cycle, then access efficiency and productivity are improved, but device complexity and layout difficulty increase
Solution Approach 1:
The memory device is segmented into multiple independent memory cells, each with its own port circuitry. This allows simultaneous access to multiple memory cells through separate ports while maintaining organized, modular layouts that reduce overall complexity
Solution Approach 2:
The patent utilizes multiple metal layers to route bit lines and word lines in three-dimensional space. By stacking conductive layers vertically, the design enables multiple access paths without increasing planar layout complexity, resolving the contradiction between simultaneous access capability and layout difficulty
2Adaptability or versatility
If multiple conductive lines in different metal layers are used to facilitate simultaneous access, then access capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The metal layer structure serves multiple functions: it provides electrical connectivity for bit lines and word lines, establishes precise alignment through standardized layer registration, and enables simultaneous access to multiple memory cells. This multi-functionality reduces the need for additional specialized structures that would increase precision requirements
Solution Approach 2:
The patent employs a hierarchical nesting structure where multiple metal layers are stacked and aligned, with each layer containing conductive lines that nest within the vertical space of adjacent layers. This nesting approach enables complex routing patterns while maintaining manufacturing precision through standardized layer registration techniques
Data Source
AI summary
A multiple-port memory cell includes first conductive lines in a first metal layer, second conductive lines in a second metal layer, third conductive lines a third metal layer, and fourth conductive lines in a fourth metal layer. The first conductive lines include a write bit line electrically coupled with a write bit line node; a first read bit line electrically coupled with a first read bit line node; and a second read bit line electrically coupled with a second read bit line node. The second conductive lines include a write word line electrically coupled with a write word line node. The fourth conductive lines include a first read word line electrically coupled with a first read word line node; and a second read word line electrically coupled with a second read word line node.