2 Replies Latest reply on Nov 16, 2017 2:58 AM by dbertocchi

    Single ended impedance in Stack Up

    expertengr

      How to calculate single ended impedance in stack up editor ? Please see in attachment I have defined the copper top and bottom thickness and also the substrate thickness and solder mask thickness. Is there any thing missing which is needed to calculate impedance for single ended trace ?

        • 1. Re: Single ended impedance in Stack Up
          kvaidya

          Characteristic impedance depends on various factors as shown in the picture below.

          Looks like for the stack up that you are using for the trace to be realistically wide enough the Z0 will have to be around 500 Ohm. As you can see I tried to replicate your stackup and to achieve Z0 as low as 390Ohm the trace would have to be around 100 mils which is highly unrealistic.

          If your design is high speed, ie if impedance mismatch is going to cause issues in the proper working of your design then, I would suggest you use an industry standards as 0.062"4 layer stack up or your particular manufacturer's guidelines or mark one of the electrical layers as a plane layer (still a bit unrealistic but definitely less than 390 Ohm.)

           

          - Kanchan Vaidya

          • 2. Re: Single ended impedance in Stack Up
            dbertocchi

            Place a plane to referring Z0

            Vaidya show Stackup editor from Hyperlynx, this is more smart then Xped/Pads