Why we need to use a differential pair为什么我们使用差分线

What is a differential pair

In its most basic form, a differential pair is two transmission lines that have equal and opposite polarity signals traveling on them. The property that these two signals have in common is that they are equal and opposite and they are tightly timed to each other. Beyond these two characteristics there are no other properties that matter when a design uses differential pairs. Maintaining the equal and opposite amplitude and timing relationship is the guiding concept when using differential pairs.


Why use differential pairs?

There are three reasons to use differential pairs in a digital or analog signal path. The most important one is that the ground
connection between the two ends of the signal path can be very poor and data quality will not be compromised.


A second reason to use differential signaling is that the link can suffer substantial attenuation of the signal and still function properly.


A third reason to use differential pairs is for data paths with very high data rates such as gigabit and higher links. It is possible to drive differential paths at rates as high as 10 Gb/S over copper traces in standard PCB materials. This is impossible to do with single-ended logic paths.