STATIC CHECKS IN RTL DESIGN : ENSURING CODE QUALITY AND RELIABILITY

Abstract

The relentless scaling of semiconductor technology and the advent of highly heteroge-neous System-on-Chip (SoC) architectures-integrating multi-core processors, high-speed interfaces, and specialized accelerators have necessitated the use of numer-ous asynchronous clock domains. While this Globally Asynchronous, Locally Syn-chronous (GALS) paradigm optimizes power and performance, it introduces severe design vulnerabilities related to Clock Domain Crossing (CDC) and Reset Domain Crossing (RDC). During asynchronous data transfers, destination flip-flops are highly susceptible to setup and hold time violations, resulting in metastability. If not manage-able, this metastable state propagates through downstream logic, causing unpredictable state corruption, signal glitches, and catastrophic system deadlocks. Traditional flat-level static verification methodologies struggle to scale with multi-million-gate de-signs. They suffer from severe memory explosion, excessive execution runtimes, and the generation of an overwhelming volume of false-positive violations. This immense "verification noise" effectively masks genuine, critical design bugs during the crucial SoC integration phase. To overcome these bottlenecks, this thesis presents an automated, hierarchical static verification framework engineered to enforce strict Register Transfer Level (RTL) code quality and guarantee highly reliable cross-domain synchronization. The methodology initiates with an automated linting protocol that acts as a rigorous first line of defense. By proactively identifying and resolving structural synthesis blockers, combinational loops, and simulation-synthesis mismatches early in the design cycle, the framework reduces structurally actionable bugs by 94% prior to dynamic functional simulation. Furthermore, the research details the implementation of a hierarchical CDC verifica-tion flow. By utilizing validated, parameterized IP-level abstract models that mask internal combinatorial depth while preserving boundary intent, the methodology fun-damentally resolves the scalability crisis of massive SoCs. This structural transition reduced top-level CDC execution runtime by 82%-dropping from an average of 14.5 hours to merely 2.5 hours and successfully suppressed hundreds of thousands of false-positive IP-level violations. Consequently, integration engineers can seamlessly isolate and resolve genuine top-level hazards, such as missing synchronizers, data loss, and logic re-convergence. Additionally, this research establishes an analytical framework for the optimization of Mean Time Between Failures (MTBF) across critical synchronizer chains. By math-ematically evaluating the structural synchronization depth, the study balances the ex-ponential gains in system reliability against the linear penalties of increased hardware latency and silicon area, ensuring the SoC meets stringent multi-decade commercial and automotive safety standards. Ultimately, this comprehensive framework achieves a true "shift-left" in the VLSI verification lifecycle. It significantly minimizes manual debugging efforts, ensures mathematically sound CDC sign-off, accelerates time-to-market, and proactively prevents the catastrophic financial impact of late-stage silicon re-spins.