RF Transmission Lines
Many of Maxim’s RF components require a transmission line with controlled impedance to transmit RF power to IC pins on the PCB. These transmission lines can be implemented on the outer layer (top or bottom layer) or buried in an inner layer. Guidelines for these transmission lines include discussions of microstrip lines, strip lines, coplanar wave guides (grounded), and characteristic impedance. It also introduces transmission line bending angle compensation and the layer change of the transmission line.
This transmission line includes a fixed-width metal trace (conductor) and a ground area located directly underneath (on the adjacent layer). For example, a microstrip on layer 1 (top metal) requires a solid ground area on layer 2 (Figure 1). The width of the trace, the thickness of the dielectric layer, and the dielectric determine the characteristic impedance (usually 50Ω or 75Ω)