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How does impedance control on a PCB track affects the components on the PCB ?

indula

New Member
I'm building a PCB which works in megahertz range that needs to be impedance matched with the measuring equipment. My question is if I added impedance control to every trace, for say 50 OHM, of the PCB will it affect the resistors and capacitors already in place and change the value seen by the other components since the traces are now 50 OHM ?
Sorry If I have misunderstood any theory behind what I'm asking since I'm newbie to the RF electronics.
 

kubeek

Well-Known Member
Most Helpful Member
Would be best if you posted your circuit. Generally the transmission line should present itself to the other components as pure 50ohm resistive impedance above a certain frequency.
 

ronsimpson

Well-Known Member
Most Helpful Member
Likely your PCB is not big enough to have a problem. Do you have a trace 1/10 wave length long?

All traces have a impedance. You probably have 200 ohm traces every where and don't know it.

If you tell the board house that you do not want " impedance control " they can make the board any way they want. When you specify impedance control then they must keep the capacitance between layers the same every time they make the board. The placement of the layers is controlled, the thickness of each layer is controlled. The board material controlled. They tell you "this wide = 50 ohms".
 
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