SystemVerilog Assertions are a formal component of the SystemVerilog standard that enable the explicit specification of design intent. They are organized into a layered structure consisting of boolean expressions, sequences, and properties, each serving a distinct role in defining expected behaviors. Boolean expressions operate at a single simulation timestep, specifying conditions such as signal equality, inequality, or stability. These form the atomic conditions that sequences and properties use to describe more complex behavior across multiple cycles. The hierarchy allows for systematic abstraction and composition of design expectations, promoting clarity and scalability in assertion-based verification.

Sequences in SVA describe temporal relationships over time. They capture the ordering, timing, and repetition of events on signal transitions across multiple cycles. Operators such as ##, [*], and within provide fine-grained control over temporal resolution. Sequence constructs allow the specification of causal behaviors, such as “if signal A is high, then signal B must follow after two cycles.” These relationships are essential for modeling realistic timing constraints and for checking protocol conformance. Additional features like fusion and intersection operators allow combining sequence expressions for compact and expressive behavior modeling.

Properties bind sequences and boolean expressions to verification semantics. They serve as containers for behavior that should or should not occur, and they are annotated with directive keywords. assert is used to check that properties always hold, assume constrains the environment in formal analysis, and cover tracks whether certain behaviors have occurred. Strong and weak operators provide semantic flexibility, determining whether a property must always eventually hold (strong) or may hold if possible (weak). These constructs collectively support the formalization of design correctness, ensuring exhaustive checking in both simulation and formal engines.

The directive keywords in SVA control how and when properties are evaluated. They define the verification intent and drive tool behavior in various flows. Assertion placement is flexible; properties can be embedded directly into RTL modules, interfaces, or instantiated in verification checkers. Different placements provide different visibility and reuse benefits. Assertions in RTL modules gain tight coupling to signals but may be less portable. Interface-based assertions improve encapsulation, while checker modules support centralized verification. Proper selection of assertion placement enhances modularity, coverage observability, and debug traceability.

Effective use of SystemVerilog Assertions depends on adherence to consistent coding patterns and precise use of syntax. Maintaining readability and structural clarity in assertions is critical for maintainability and review. The SVA subset covered in practical design flows focuses on essential operators and constructs that provide the maximum benefit with minimal overhead. A disciplined approach to writing, organizing, and reviewing assertions ensures that they serve as enforceable rules that directly reflect the design specification. When properly deployed, assertions become integral to the verification methodology, enabling faster debug, improved coverage, and higher confidence in functional correctness.