Impedance Printed Circuit Board
The characteristic impedance of the conductor on the printed circuit board is an important indicator of the PCB design. Especially in the circuit design of a high frequency PCB board, if the characteristic impedance of the conductor is the same with the required one by the device or signal.
According to the signal transmission theory, the signal is a function of time and distance variables, so the signal may change in every part of the connection. Therefore, the connection of the AC impedance needs to be determined, that is, the ratio of the change in voltage to the change in current is the characteristic impedance of the transmission line which only depends on the nature of the signal connection itself.
In the actual circuit, the resistance of the wire itself is less than the distribution impedance of the system, especially the impedance PCB board is a high-frequency PCB board. The characteristic impedance mainly depends on the distributed impedance due to the unit distributed capacitance and the unit distributed inductance.
The rising edge of the signal and the signal transmission to the receiving end of the proportion of time required determine whether the signal connection is seen as a transmission line. For example: if the PCB board wiring length is greater than l/b, then it can be connected between the signal wires as a transmission line.