What is circuit board impedance

What is board impedance ? The blocking effect of alternating current in a circuit board is called impedance. Impedance is generally represented by Z, which is a complex number. The real part is called resistance and the imaginary part is called reactance. The blocking effect of capacitance on alternating current in the circuit is called capacitive reactance, the blocking effect of inductance on alternating current in the circuit is called inductive reactance, and the blocking effect of capacitance and inductance in the circuit on alternating current is collectively called reactance. Let's take a look with me.

Board characteristic impedance

In electronic information products such as computers and wireless communications, the energy transmitted in the PCB circuit is a square wave signal (called a pulse) composed of voltage and time. The resistance it encounters is called the characteristic impedance.

Board Differential Impedance

The driving end inputs two identical signal waveforms with opposite polarities, which are respectively transmitted by two differential lines, and the two differential signals are subtracted at the receiving end. Differential impedance is the impedance Zdiff between two wires.

Board Odd Mode Impedance

The impedance value to ground from one line to the two lines is the same, and the impedance value of the two lines is the same.

Board Even Mode Impedance

The driving end inputs two identical signal waveforms with the same polarity, and the impedance when the two wires are connected is Zcom.

Board Common Mode Impedance

The impedance Zoe of one of the two lines to ground is the same as the impedance of the two lines, and is usually greater than the odd-mode impedance.