Impedance Calculation

In modern devices signals are operating at higher frequencies, rising and falling edges are reduced (1 ns or less), and the frequency is increased (to tens of GHz). This requires the use of printed circuit boards (PCBs) with controlled impedance in order to prevent distortion of the signal when it is transmitted over the conductors. A conductor on a PCB is no longer just a track linking the contact pads and vias, but a transmission line that has to transmit a signal with low loss of shape, amplitude, and velocity.
When designing a PCB, the developer must determine which layers contain impedance-controlled conductors (or differential pairs) and which layers contain ground and power reference layers. The developer’s task is to perform preliminary calculations of the PCB structure and design it taking into account the calculated values of the conductor width in the specified layers.
Modern CAD for PCB design should support different transmission line structures and consider as many parameters that can affect the calculation of impedance as possible. The impedance calculator must use the most accurate formulas for calculation. Controlled impedance of PCBs raises the process of design, material selection, structure, and production of PCBs to a new level.