Comprehensive analysis on different power integrity signoff methodologies and development of a novel flow with augmented coverage on critical timing paths

The design and fabrication of Integrated Circuits (ICs) have become increasingly complex with the advancement of semiconductor technology and the move to smaller process nodes. As chip designs grow in scale and functionality, ensuring that a design is robust, reliable, and manufacturable becomes paramount. Sign-off in the semiconductor design process is the final stage of verification before a chip design is sent for manufacturing. It ensures the design meets all necessary specifications and quality requirements, avoiding costly errors in production. Sign-off typically involves a series of checks and analyses across different aspects of the design to guarantee functionality, reliability, and manufacturability. Sign-off encompasses a variety of critical checks, including Static Timing Analysis (STA), Power Integrity (PI) verification, Signal Integrity (SI) checks, and physical verification steps such as Design Rule Check (DRC) and Layout Versus Schematic (LVS). These processes ensure that the chip operates correctly under all possible scenarios, adheres to the foundry’s fabrication constraints, and meets the intended power-performance-area targets. Power Integrity is a critical aspect of modern electronic design, ensuring that power delivery networks (PDNs) provide stable and reliable power to Integrated Circuits (ICs) without excessive noise, voltage drops, or reliability issues. As semiconductor technologies advance to smaller nodes and higher operating speeds, maintaining power integrity becomes increasingly complex due to reduced noise margins, higher power density, and stringent timing requirements. One of the most critical challenges in power integrity is managing voltage stability, particularly the effects of IR drop. IR drop occurs when current flows through resistive and inductive elements in the power grid, leading to a voltage drop that can cause functional failures in a chip. It is categorized into two types; Static IR Drop and Dynamic IR Drop. Static IR Drop that also known as DC IR drop, refers to the steady-state voltage drop in the power delivery network (PDN) due to the resistive nature of metal interconnects. This type of voltage drop occurs when current flows through the power grid, causing a voltage reduction due to the inherent resistance of the wires. static IR drop is constant and depends on the total current consumption of the design in a worst-case scenario. Dynamic IR Drop also known as AC IR drop, refers to transient voltage fluctuations in a PDN caused by rapid changes in current due to simultaneous switching of logic gates. Unlike static IR drop, which assumes a constant DC current, DVD accounts for the time-varying nature of current consumption in a real circuit, making it a more accurate measure of power integrity. Excessive dynamic voltage drop can cause timing failures due to slower signal transitions, functional errors if voltage drops below the minimum operating level, and Reduced noise margins, leading to unpredictable circuit behavior. Several methodologies have been proposed to analysis dynamic voltage drop. Generally, they are categorized into two overall flows, vectorless DVD and vector-based DVD. Vectorless Dynamic Voltage Drop (DVD) analysis is a method used to estimate transient voltage drops in an Integrated Circuits (IC) without requiring explicit switching activity vectors. Instead of using real simulation waveforms, vectorless analysis relies on statistical and probabilistic models to estimate current consumption patterns and identify w