The document addresses the gap between theoretical circuit design and successful hardware implementation. It introduces 'Murphy's Law' as a framework for understanding how non-ideal components and parasitic elements from circuit layout can cause unexpected failures in mixed signal systems.
Key physical phenomena discussed include the resistance of conductors (such as PCB tracks), the skin effect at high frequencies, voltage drops in signal leads, and leakage currents through insulators. The text provides calculations for bit sizes in converters and specific examples regarding copper resistivity and PCB track dimensions.
| Resistivity of pure copper at 25°C | 1.724E-6 ohm cm |
|---|---|
| Thickness of standard PCB foil (1 ounce) | 0.088 mm |
| Resistance of standard PCB copper per square | 0.45 milliohms/square |
| Temperature coefficient of resistance for copper | about 0.4% MC around room temperature |
The document lists Ohm's Law, Kirchhoff's Law, Faraday's Laws, and Lenz's Law as the basic physics principles involved.
Skin effects must be considered at frequencies above approximately 12 MHz for this type of PCB foil.