Multiport Memory Word Line Pitch Asymmetry for Noise Margin
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Solution Overview
Problem
In multiport semiconductor devices, interference between different ports leads to challenges in predicting and managing noise margins, particularly due to asynchronous operation and complex phase relationships, making it difficult to secure sufficient noise margins without increasing circuit area.
Innovation Solution
The semiconductor device employs a configuration with alternating pitches between word lines for different ports, along with the use of shield lines between control signals and selector circuits, to reduce interference and expand noise margins while minimizing area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If word lines for different ports are disposed alternately at equal pitch to reduce coupling noise, then noise reduction is achieved, but interference between different ports increases making noise margin prediction difficult
Solution Approach 1:
The patent applies asymmetry by disposing word lines for different ports at different pitches rather than equal pitches. Specifically, the pitch between word lines of different ports is made larger than the pitch between word lines of the same port, creating an asymmetric layout that reduces inter-port interference while maintaining intra-port noise reduction benefits
Solution Approach 2:
The patent applies local quality by making the pitch between word lines location-dependent: smaller pitch between same-port word lines for noise reduction, and larger pitch between different-port word lines for interference reduction. This localized variation in spacing optimizes both noise reduction and interference management in different regions of the layout
2Reliability
If shield lines are added between control signals and selector circuits to reduce interference, then noise margin is expanded, but device complexity increases
Solution Approach 1:
The patent introduces shield lines as intermediary elements between control signals and selector circuits. These shield lines act as mediators that block or reduce interference between different signal paths, thereby expanding noise margins without requiring fundamental changes to the core circuit architecture
Solution Approach 2:
The patent segments the circuit into distinct regions with controlled interference characteristics by inserting shield lines between different functional blocks. This segmentation isolates control signals from selector circuits, managing interference through spatial division rather than complex temporal coordination
Data Source
AI summary
A semiconductor device enabling expansion of a noise margin. For example, in a memory area in which each memory cell MC is coupled to a word line WLA for a first port and a word line WLB for a second port, and a plurality of memory cells MC are disposed in a matrix shape, each word line is disposed in the order of WLA0, WLB0, WLB1, WLA1, WLA2. Further, a pitch d2 between WLA-WLA and between WLB-WLB is made smaller than a pitch d1 between WLA-WLB. As such, the word lines of an identical port are disposed at the pitch d2 on one of both sides of a certain word line and the word lines of different ports are disposed at the pitch d1 on the other.