Standard Cell Types

Overview

Standard cells are pre-characterized logic elements used to build digital designs. Each cell comes in multiple drive strengths and often multiple threshold voltage options, allowing tradeoffs between speed, power, and area.

A healthy library includes combinational logic, sequential elements, clock cells, and special-purpose cells that protect signal integrity and manufacturability.

Common Cell Categories

Combinational cells (inverters, NAND/NOR, AOI/OAI) form the logic fabric.

Sequential cells (flip-flops, latches) capture state and define timing boundaries.

Clock and CTS cells (buffers, inverters, clock gates) manage skew and insertion delay.

Special cells (tie-high/low, level shifters, isolation, retention) support low-power and multi-voltage designs.

Physical only cells (tap, endcap, filler, decap) ensure well integrity and DRC compliance.

Selection Tips

Use higher drive cells only on critical paths or heavy loads.

Prefer high-Vt cells for leakage control and low-Vt on timing-critical paths.

Keep clock networks on dedicated clock cells to minimize jitter and skew.

Related Topics

• Delay Models
• Static Timing Analysis
• Physical Design Cells