Programmable Logic Cells With Post-Fabrication Delay Tuning
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Solution Overview
Problem
Integrated circuits (ICs) face significant performance variability due to process variations, supply voltage changes, and environmental factors, leading to increased worst-case cell delays and inefficiencies in traditional logic design methods, which require additional margins and complex statistical timing analysis.
Innovation Solution
The implementation of programmable digital logic cells with tunable circuitry and voltage controllers that allow for calibration and adjustment of processing speed based on calibration data, enabling fine-grained control over performance characteristics such as cell delay, rise time, and fall time, using fuses or switches for programming and selective coupling of tuning circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional logic design methods are used to account for process variations, then design reliability is improved, but worst-case cell delays increase significantly
Solution Approach 1:
The patent applies dynamics by making the logic cell's drive strength adjustable rather than fixed. Tuning circuitry is integrated into each logic cell, allowing the drive strength to be dynamically modified after fabrication. This enables the cell to adapt its performance characteristics to compensate for process variations, thereby reducing worst-case delays while maintaining design reliability.
Solution Approach 2:
The patent changes the drive strength parameter of the logic cell through integrated tuning circuitry. By modifying the effective drive strength parameter of the logic cell, the patent compensates for process variations and reduces worst-case cell delays. The tuning circuitry adjusts parameters such as transistor width or resistance to achieve the desired delay compensation.
2Ease of manufacture
If standard drive strengths are used for all logic cells, then manufacturing simplicity is improved, but performance variability increases
Solution Approach 1:
The patent segments the logic cell into functional components: the core logic function block and separate tuning circuitry. This segmentation allows the core logic to be manufactured with standard processes while the tuning circuitry provides individualized performance adjustment. Each logic cell can be independently tuned, enabling precise performance control without complicating the overall manufacturing process.
Solution Approach 2:
The patent incorporates tuning circuitry and calibration capabilities into the logic cell during manufacturing, preparing it for subsequent performance adjustment. The tuning circuitry is pre-integrated with control interfaces that enable post-fabrication calibration, allowing performance variability to be corrected without requiring complex manufacturing processes.
3Manufacturing precision
If tuning circuitry is integrated into each logic cell, then performance variability is reduced, but device complexity increases
Solution Approach 1:
The patent merges the tuning circuitry with the logic cell structure, integrating performance adjustment functionality directly into the logic cell. This consolidation reduces the need for separate external tuning components and simplifies the overall system architecture. The tuning circuitry shares resources with the logic cell, such as power supplies and control signals, thereby minimizing the increase in device complexity.
Solution Approach 2:
The tuning circuitry is designed to be universal and multi-functional, capable of adjusting multiple performance parameters across different logic cell types. The same tuning circuitry architecture can be applied to various logic cell configurations, reducing design complexity and enabling standardized manufacturing approaches despite the added functionality.
4Measurement precision
If mathematical models and statistical timing analysis are used, then timing accuracy is improved, but analysis complexity and development time increase
Solution Approach 1:
The patent enables the logic cell to self-calibrate its performance characteristics through integrated tuning circuitry. The cell automatically adjusts its drive strength based on measured performance parameters, eliminating the need for complex external statistical timing analysis. This self-service approach simplifies the design process while maintaining high timing accuracy through direct performance measurement and adjustment.
Solution Approach 2:
The patent implements feedback mechanisms where the logic cell's performance is measured and used to control the tuning circuitry. This closed-loop feedback system automatically compensates for timing variations without requiring complex pre-analysis or statistical modeling. The feedback approach simplifies development by enabling direct empirical optimization rather than relying on mathematical models.
Data Source
AI summary
An integrated circuit (IC) includes at least one programmable digital logic cell that includes first dedicated digital logic cell having a plurality of transistors including at least one PMOS transistor and at least one NMOS transistor configured to perform at least one digital logical function. The first dedicated digital logic cell includes a plurality of nodes including at least one input node and at least one output node that reflects performance of a digital logical function. Programmable tuning circuitry includes at least one tuning input and at least one tuning circuit output. Circuitry for coupling or decoupling the tuning input or tuning circuit output to at least one of the plurality of nodes of the first dedicated digital logical cell is provided, wherein the coupling or decoupling is operable to change the processing speed for the first reprogrammable digital logic cell.