Issue link: https://resources.pcb.cadence.com/i/1534337
3. Ground Bounce and Power Distribution Noise (PDN) Showing how the voltage drops or rises depending on capacitors that were used f Problem: In high-speed designs, rapid switching events cause fluctuations in ground and power planes, known as ground bounce and rail collapse, respectively. This creates power distribution noise, affecting the stability of signals and increasing the risk of data errors. f Solution: See PDN Explanation and Design Steps below (and why it is complicated to calculate) Designing an optimized Power Distribution Network (PDN) is crucial for ensuring clean and stable power delivery to your circuit, which directly impacts its performance and reliability. A PDN is essentially the pathway that delivers power from the source to the various components within your circuit. This includes the power and ground traces on your PCB, decoupling capacitors, vias, and any other elements involved in power distribution. Why PDN Matters: f Current flow and impedance: As current flows through the copper traces on your PCB, the inherent impedance of these traces can cause voltage drops and generate noise. f Component sensitivity: Excessive noise and voltage fluctuations can disrupt the operation of sensitive components and lead to malfunctions or even damage. f Signal integrity: Noise on the power supply can also couple into signal lines, degrading signal integrity and affecting overall circuit performance. PDN Design is NOT just analysis: While PDN analysis tools are valuable for identifying potential problem areas, effective PDN design starts at the initial stages of your project. Key aspects include: 1. Minimizing trace impedance: Careful selection of trace widths and lengths for power and ground (use wide traces or copper pour wherever possible), along with proper via placement (stitching vias and fanouts), helps to minimize impedance and reduce voltage drops. 9 www.cadence.com OrCAD X High-Speed Digital Design Guide