Some areas of physics have considerable impact on PCB designs.

PCB designers have had exposure to electronics (some more than others). And most of what we do falls under the field of electronics. But designers often have little or no exposure to physics. And some areas of physics have considerable impact on our designs. Here we look at two physical properties of the dielectrics we work with, and why they are important to understand (Note 1).

Understanding reflections caused by transmission line characteristic impedance and termination impedance mismatch.

Analysis of “digital interconnects” is the analog problem in frequency domain where interconnects are simulated as transmission lines defined by characteristic impedance and propagation constant. Digital signals in interconnects are sequences of amplitude-modulated pulses that transmit bits between components. The “digital interconnect” analysis problem is technically an analog problem of pulse propagation modeling in time-domain.