Advanced Signal Integrity for High-Speed Digital Designs

5

NONIDEAL CONDUCTOR MODELS

5.1 Signals Propagating in Unbounded Conductive Media

5.1.1 Propagation Constant for Conductive Media

5.1.2 Skin Depth

5.2 Classic Conductor Model for Transmission Lines

5.2.1 DC Losses in Conductors

5.2.2 Frequency-Dependent Resistance in Conductors

5.2.3 Frequency-Dependent Inductance

5.2.4 Power Loss in a Smooth Conductor

5.3 Surface Roughness

5.3.1 Hammerstad Model

5.3.2 Hemispherical Model

5.3.3 Huray Model

5.3.4 Conclusions

5.4 Transmission-Line Parameters for Nonideal Conductors

5.4.1 Equivalent Circuit, Impedance, and Propagation Constant

5.4.2 Telegrapher’s Equations for a Real Conductor and a Perfect Dielectric

References

Problems

As digital systems evolve and technology pushes for smaller and faster designs, the geometric dimensions of the physical platform are shrinking. Smaller dimensions and higher data transmission rates necessitate the use of proper techniques to model both the frequency dependent resistive losses and inductance. Without proper models that accurately predict these quantities, simulation-based bus design for multigigabit data rates is not possible. Frequency-dependent resistive losses, for example, will affect bus performance by decreasing the signal amplitude and slowing edge rates, which in turn affects voltage and timing margins, respectively. In addition, frequency dependent inductance models are required to preserve causality , which is discussed in Chapter 8 and Appendix E. In prior days it was possible to utilize ...