Gatelevel

Gatelevel or gate-level design is a level of digital circuit design where circuits are described exclusively by logic gates and their interconnections, often captured as a gate-level netlist or schematic. It sits below the higher-level RTL (register-transfer level) in the abstraction hierarchy and above transistor-level models in some descriptions. In gate-level design, the function is implemented using gates such as AND, OR, NOT, NAND, NOR, XOR, and XNOR, along with basic memory elements like D flip-flops and latches. The netlist specifies gate types, input and output pins, and connectivity, and includes timing information in the form of gate delays.

In typical design flows, higher-level RTL code is synthesized into a gate-level netlist using a standard cell library or target technology. The gate-level representation is then used for physical design steps such as place-and-route. Gate-level designs provide more accurate timing and area estimates than RTL, but are less portable across technologies than transistor-level models and can be more sensitive to glitches and hazards if not properly buffered and synchronized.

Key aspects of gate-level design include timing analysis to ensure setup and hold times for sequential elements, area optimization, and power estimation based on gate-level delays. Libraries of standard cells or gates define the available building blocks, their drive strengths, and delays, which constrain the final implementation. While many modern flows use higher-level abstractions up to gate-level for back-end processes, gate-level representations remain essential for accurate timing-driven placement, routing, and verification in digital ASIC design.