High Frequency Termination Resistors

Discussion in 'General Electronics Chat' started by Skeebopstop, Feb 13, 2013.

  1. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    Hey All,

    we've been getting into some 6GHz SDI style communications at work. Crazy stuff.

    Anyways, been looking at the manufacturers recommended termination scheme for our line equalizers and all the rave now are 'anti-pads'. Basically, keep all the planes cut out underneath your 50 Ohm resistor except for the bottom layer (bottom layer being GND, only so EMI doesn't leak up the antipad hole).

    I see a few concerns with this strategy, however though I do agree with it in principle as coupling capacitance to planes is unwanted when you want a purely resistive termination. However there will be a slight blip in the return path for high frequency currents etc.. given the antipad.

    What I am surprised to find is that I am having a difficult time finding RF grade components suited towards tackling this problem with 3 terminal resistors where the 3rd terminal creates a controlled capacitance that has a strong low inductance bond to your GND plane, or something of this accord.

    Does anyone know if there is anything going around like this? It would just be great to not have to worry about these Anti-pads all the time going forward.