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 ?
I think this is a sensible answer - but you may get another more helpful one. I'm a microwave engineer not a low frequency engineer (100 MHz is low frequency for me). At microwave frequencies the tracks do have to be 50 ohms, but not all of them.
I presume you mean you want the output, and perhaps the input, to be matched to 50 ohms. You will not achieve this by making all the traces 50 ohms unless you circuit is very simple. You need to use reactive components at the output and perhaps the input to cancel any remaining reactive impedance seen at these ports, and transformers to change the remaining real impedance to 50 ohms. There are probably filter designs that will do this. You should be able to find the impedance at the input and output fairly easily using a simulation program. If you are at 100 MHz the wavelength is about 2 m in-board and all your components are so close together, in terms of fractions of a wavelength, or degrees phase, that you don't need to treat things as transmission lines. If something is 1 cm long it is only a 1/200 wavelength (1.8 degrees) long transmission line. A high-impedance (narrow) line this long may introduce series inductance, but not much, and if it's too wide it may introduce shunt capacitance, but not much. This means that short lines don't have much effect and also that using transmission line components to match is not feasible because they will be longer than is convenient.
Z. Skvor The board size is 102mm * 152.4mm and it operates in 13.56 MHz.
Malcolm White Thank you for your good answer with detailed explanation.
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