5.1.7. Understanding Transmission Lines
The transmission line is a trace and has a distributed mixture of resistance (R), inductance (L), and capacitance (C). There are two types of transmission line layouts:
Figure 70 shows a microstrip layout, which refers to a trace routed as the top or bottom layer of a PCB and has only one voltage-reference plane (i.e., power or GND). Figure 71 shows a stripline layout, which uses a trace routed on the inside layer of a PCB and has two voltage-reference planes (i.e., power and/or GND).