Enhanced immunity against crosstalk and EMI using GHz twisted differential line structure on PCB

There is a growing tendency to adopt a differential signaling scheme for critical signals. To support differential signaling, differential transmission lines are required. The concept of twisted pair on the cable interconnection can be readily applied to differential transmission lines on printed circuit boards (PCBs), which enables enhanced immunity against crosstalk and radiated emission. The new differential transmission line called twisted differential line (TDL) has been introduced. In this paper the enhanced immunity of TDL against crosstalk and radiated emission is clearly demonstrated with both simulation and measurement. TDL is compared with other differential transmission lines showing its superiority. Moreover several ideas to improve the performance of TDL are proposed and verified to be useful. Offset-TDL (O-TDL) improves crosstalk immunity further and vertical-TDL (V-TDL) enables reduced routing area while maintaining performance.