PLD design methodology — naming the building-block approach In programmable logic device (PLD) development, what is the design concept called where complex systems are constructed from reusable circuit “blocks” arranged in levels?

Introduction / Context:
When targeting PLDs, CPLDs, or FPGAs, engineers routinely assemble larger functions from smaller, well-tested modules. This modular thinking supports clarity, reuse, and verification at multiple abstraction layers, and it is central to scalable hardware development flows.

Given Data / Assumptions:

• Goal: name the design paradigm built around reusable blocks.
• Context: PLD projects, but the concept applies broadly in digital design.
• Blocks can be RTL modules, IP cores, or schematic macros.

Concept / Approach:
Hierarchical design organizes a system into layers: leaf modules implement primitive functions; mid-level modules compose these into subsystems; a top-level integrates all subsystems. This hierarchy enables focused simulation, easier timing closure, and team-based parallel development, while also easing incremental synthesis and floorplanning in larger devices.

Step-by-Step Solution (Reasoning):

Verification / Alternative check:
Industry practice: vendor reference designs and IP catalogs are organized hierarchically (e.g., UART block inside a communication subsystem inside a SoC). Synthesis and static timing tools exploit hierarchical boundaries to manage complexity.

Why Other Options Are Wrong:

• Architectural design: addresses system-level choices, not the specific building-block method.
• Digital design: overly broad; not a methodology name.
• Verilog: a hardware description language; not a design paradigm.
• Behavioral synthesis: a tool technique, not the general building-block concept.

Common Pitfalls:

• Confusing language (Verilog/VHDL) with methodology (hierarchy, top-down/bottom-up).

Final Answer:
hierarchical design.