Tape-Out Readiness Checklist: Engineering Decisions That Prevent Costly Respins

Tape-out is the moment when an ASIC design moves from being a plan to becoming a real chip. At this stage, functional behaviour, timing, power, physical layout, testability, and manufacturability must all be well understood and verified.

A design might work correctly on paper but still fail in practice due to issues such as clock domain crossings (CDC), incorrect timing rules, voltage drops (IR), electromigration (EM), routing problems, or problems that arise during manufacturing.

Fixing these after tape-out is very costly.

A strong tape-out process should fix problems step by step, not just check things once at the end before releasing the final design files (GDSII).

Phase 1: Front-End Architecture and RTL Sign-Off

RTL Linting, CDC, and RDC Verification

Issues like unintended latches, signals from multiple sources, incomplete assignments, crossings between clock domains, and crossings between reset domains can go undetected until the chip is made.

Formal checks for CDC and RDC should make sure that the behavior of asynchronous signals and resets is correct. Special attention is needed for situations that could cause unstable signals, reset order, and how synchronizers are used.

Any exceptions should be checked and recorded before finalizing the RTL design.

Functional Verification Closure

Functional testing should cover both normal operation and rare situations that are hard to reach with simulation.

Using constrained-random UVM tests gives a wide range of inputs, while formal verification helps prove correct behavior in parts of the design that are controlled, like arbiters, decoders, state machines, and protocol managers.

Testing should cover all parts of the code, like statements, branches, changes, and state machines, as well as functional coverage.

The goal is not just to reach a high percentage, but to understand why some parts are not covered. Every missing part should have a reason and be checked by others.

Power Intent Verification

Features like multiple voltage levels, power gates, isolation cells, level shifters, and power-saving elements must work together across different power modes.

The power intent language (UPF or CPF) should match the RTL and the final design.

Testing should check how the chip behaves during power-up, power-down, isolation, retention, and wake-up steps to make sure everything works properly when changing power modes.

Phase 2: Synthesis and Netlist Sign-Off

SDC Constraint Validation

Missing clocks, wrong definitions for generated clocks, false paths, paths that take more than one cycle, and inputs that are not constrained can result in incorrect timing analysis.

SDC constraints should be checked for correct syntax, completeness, consistency, and proper intent.

Relationships between clocks should be clearly defined, not left for the tool to guess. Every timing exception should have a clear reason and be reviewed as part of timing sign-off…………………….

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