1. Global Circuit Page 1  Basic Design Rule for Advanced PCB (1) 1. High speed current path Load Driving gate Current trace At low frequency current, follows the path of least resistance Load Current trace Driving gate High-speed Return current Stays tightly bunched under Signal trace At high frequency current, follows the path of least inductance

2. Global Circuit Page 2  Basic Design Rule for Advanced PCB (2) 2. Induction of slot on Ground plane I.C. Return current Signal trace Hole clearance on ground plane Equivalent circuit showing inductance in the return path. This inductance is approximately 1nH/cm. Signal trace Return current on ground place

3. Global Circuit Page 3  Basic Design Rule for Advanced PCB (3) Signal trace Via w w w w www w 3W 3W rule is to minimize coupling between trace and signals by providing “clean path” and by aligning the signal flux and the return flux. ☞ Minimize RF fringe between traces ☞ Reduce cross-talk between traces without ground guards Ground Plane 3. Trace 3W rule

4. Global Circuit Page 4  Basic Design Rule for Advanced PCB (4) 4. Inductive & Capacitive Cross-talk Vs Zo source victim Zo

5. Global Circuit Page 5  Basic Design Rule for Advanced PCB (5) 5. Concept of transmission line Trace width Copper thickness Dielectric Copper plane Dielectric thickness h C Micro strip trace PCB laminate Plane Micro-strip Plane Dielectric Signal layer Strip-line Dual Strip-line

6. Global Circuit Page 6 High speed PCB design requires consideration of: –Signal Propagation (Ringing & Reflection), –Interaction between signals (Cross-talk, Electro-Magnetic Interference) High Speed PCB performance needs: –To select suitable material (FR-4, BT, Polyimide, …) –Good process control : Stack up of layers, especially for multi layers Uniform and stable impedance (R, L, C)  Basic Design Rule for Advanced PCB (6) 6. Conclusion