multi-finger transistor

**Multi-Finger Transistor** is a **layout technique where a wide transistor is split into multiple parallel "fingers"** — each finger being a narrow gate stripe, connected in parallel, to reduce gate resistance and improve high-frequency performance. **What Is a Multi-Finger Layout?** - **Instead of**: One gate with W = 100 $mu m$ (very long, high $R_g$). - **Use**: 20 fingers, each with W = 5 $mu m$ (short, low $R_g$ per finger). - **Connection**: All gates, drains, and sources connected in parallel via metal routing. - **Total Width**: $W_{total} = N_{fingers} imes W_{finger}$. **Why It Matters** - **$R_g$ Reduction**: Gate resistance drops as $1/N^2$ with interdigitated layout. - **$f_{max}$ Improvement**: Directly improves maximum oscillation frequency. - **Thermal Distribution**: Spreads heat across a larger area vs. a single wide device. **Multi-Finger Transistor** is **parallelism at the device level** — dividing a transistor into many thin slices for better resistance, performance, and thermal management.