Hello,
I have problem with understanding differential nature of DC coupled CML pair in TDMS (DVI, HDMI). In DC coupled LVDS current flows from source through one wire of transmission line then through termination resistor and goes back through second line to source. So currents are equal and they flow in opposite direction. Loop is formed by source, differential pair and termination resistor. In CML pair current flows only in one line at the same time, second line is disconnected. If I have understood it good return current has to flow in ground plane. Loop is formed by source, one line from differential pair, termination resistor, VCC plane, decoupling capacitor, ground plane. Does it make ground connection between for example two PCBs extremely crucial? Does sending TMDS signal through twisted pair CAT cable depends highly on good shield connection between systems because this is conductor through which return currents flow ?
Best Regards, inv___
--------------------------------------- Posted through