Multi-Vt D Flip-Flop Layout for Hold-Slack and Data-Race Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing scan-insertion D flip-flops (SDFQs) face challenges in avoiding hold-slack violations without increasing the area/footprint or eliminating critical components, which can lead to data-racing issues and inefficiencies in semiconductor devices.
Innovation Solution
The implementation of SDFQs with a mix of threshold voltages, including standard (Vt_std), low (Vt_low), and high (Vt_high) threshold voltage transistors, which allows for the retention of necessary components like the fourth NS inverter while optimizing transistor arrangement to prevent hold-slack violations and data-racing problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SDFQ design is used, then area/footprint is reduced, but hold-slack violations occur
Solution Approach 1:
The patent applies local quality by assigning different threshold voltage characteristics to different transistor groups within the SDFQ circuit. Specifically, transistors in the fourth non-sleepy inverter are configured with different threshold voltages compared to other transistors, creating localized electrical property variations that prevent hold-slack violations without requiring global circuit redesign.
Solution Approach 2:
The patent changes the electrical parameters of transistors by utilizing multiple threshold voltage variants (standard, low, and high threshold voltage transistors). This parameter variation allows optimization of the fourth non-sleepy inverter's performance to prevent hold-slack violations while maintaining overall circuit functionality.
2Reliability
If fourth NS inverter is eliminated to avoid hold-slack violations, then area/footprint is reduced, but data-racing issues occur
Solution Approach 1:
Rather than eliminating the fourth non-sleepy inverter entirely, the patent applies local quality by modifying only the threshold voltage characteristics of transistors within this specific inverter. This localized modification maintains the inverter's data-racing prevention function while avoiding the need to remove the component structure.
Solution Approach 2:
The patent changes the threshold voltage parameters of transistors in the fourth non-sleepy inverter to achieve proper timing margins and prevent hold-slack violations. This parameter adjustment allows the inverter to maintain its protective function without requiring structural elimination.
3Productivity
If transistor density is increased, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by concentrating threshold voltage differentiation in specific transistor groups (particularly the fourth non-sleepy inverter) rather than requiring precise control across all transistors. This localized approach allows higher overall transistor density while maintaining manufacturing feasibility through focused precision requirements.
Data Source
AI summary
A semiconductor device includes: a cell region including active regions where components of transistors are formed; the cell region are arranged to function as a D flip-flop that includes a primary latch (having a first sleepy inverter and a first non-sleepy (NS) inverter), a secondary latch (having a second sleepy inverter and a second NS inverter), and a clock buffer (having third and fourth NS inverters). The transistors are grouped: a first group has a standard threshold voltage (Vt_std); a second group has a low threshold voltage (Vt_low); and an optional third group has a high threshold voltage (Vt_high). The transistors which comprise the first or second NS inverter have Vt_low. Alternatively, the transistors of the cell region are further arranged to function as a scan-insertion type of D flip-flop (SDFQ) that further includes a multiplexer; and the transistors of the multiplexer have Vt_low.