SRAM Memory Cell With P-Type Diffusion Read-Only Port
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Solution Overview
Problem
Current SRAM memory cell designs face challenges in noise margin and area efficiency, with 6T SRAM cells having poor noise margin and 8T SRAM cells requiring large silicon substrate areas and not satisfying p-type diffusion requirements.
Innovation Solution
A memory cell design incorporating a bistable element with p-channel transistors and a p-type diffusion read-only port, which includes forming a bistable element with data storage nodes and coupling p-channel transistors in series, with the read-only port formed over a p-type diffusion region to meet semiconductor fabrication requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If 6T SRAM cell design is used, then area efficiency is improved, but noise margin deteriorates
Solution Approach 1:
The memory cell is segmented into functional blocks including a bistable element, a write port with n-channel transistors, and a read-only port with p-channel transistors. This segmentation allows each section to be optimized independently, achieving compact area while maintaining sufficient noise margin through the dedicated read-only port structure.
2Reliability
If 8T SRAM cell design is used, then noise margin is improved, but area efficiency deteriorates
Solution Approach 1:
The read-only port functionality is extracted as a separate dedicated structure with p-channel transistors, distinct from the write port. This extraction allows the read path to be optimized for noise margin independently, while the overall cell area is reduced compared to full dual-port 8T designs by consolidating write and read functions into a unified structure.
3Reliability
If 8T SRAM cell design is used, then noise margin is improved, but p-type diffusion requirement is not satisfied
Solution Approach 1:
The read-only port is implemented with p-channel transistors formed over a p-type diffusion region, creating a localized area with the required p-type characteristics. This local quality adjustment satisfies the manufacturing p-type diffusion requirement specifically where needed for the read path, while the rest of the cell can be optimized for area efficiency.
Data Source
AI summary
A memory cell includes a bistable element and two p-channel transistors (i.e., first and second p-channel transistors). The bistable element includes a plurality of inverting circuits and at least one data storage node. The bistable element may be formed in a first region on the substrate that is partially formed by a p-type diffusion region and an n-type diffusion region. The first and second p-channel transistors are coupled serially. The first p-channel transistor may also have its gate terminal coupled to the at least one data storage node of the bistable element. A method of manufacturing the memory cell includes forming a bistable element having at least first and second data storage nodes, forming a write-only port of the memory cell over an n-type diffusion region and forming a read-only port of the memory cell over a p-type diffusion region.