差分走线的规则--真理与虚论
单端与差分比较，写的比较专业We generally think of signals propagating through our
circuits in one of three modes, single-ended, differential mode,
or common mode.
Single ended mode is the mode we are most familiar with.
It involves a single wire or trace between a driver and a receiver.
The signal propagates down the trace and returns
through the ground system1
Differential mode involves a pair of traces (wires) between
the driver and receiver. We typically say that one trace
carries the positive signal and the other carries a negative signal
that is both equal to, and the opposite polarity from, the
first. Since the signals are equal and opposite, there is no return
signal through ground; what travels down one trace
comes back on the other.
Common mode signals are typically more difficult to understand.
They may involve either single-ended traces or two
(or perhaps even more) differential traces. The SAME signal
travels along both the trace and its return path (ground) or
along both traces in a differential pair. Most of us tend to be
unfamiliar with common mode signals because we tend never
to intentionally generate them ourselves. They are usually the
result of noise being coupled into the circuit from some other
(nearby or external) source. Generally, their consequences are
neutral, at best, or damaging at worst. Common mode signals
can generate noise that interrupts the operation of our circuits,
and are a common source of EMI problems.
【文件名】:09813@52RD_differentialrules.pdf
【格 式】:pdf
【大 小】:132K
【简 介】:差分走线
【目 录】:差分走线 【文件名】:09813@52RD_differential design rules.pdf
【格 式】:pdf
【大 小】:199K
【简 介】:
【目 录】:
[描述差分走线中的注意事项，以及为什么要等长，有时候等长比靠近更重要，即使低频也要等长，写的非常好
摘录部分 内容:
There is no shortage of design rules available when people talk about differential traces on circuit
boards. At various times you can hear people argue that there is a need for, or there is no need for, a
variety of special rules. In general, the rules fall into one or more of these five categories:
Planes: There must be a continuous power system plane underneath the differential pair.
Length: Care must be taken to ensure that differential traces are of equal length.
Spacing 1: Care must be taken to place the traces as close together as possible.
Spacing 2: Care must be taken to ensure that the spacing between traces is constant
everywhere along the length of the traces.
Impedance: Differential impedance rules must be applied.
So let’s set the record straight about these rules right now. NONE of them are inherently required by the
fact that we are using differential signals! There is nothing about differential signals that necessitates any
of these rules in any ordinary design.
But some of them might be required if we are worried about signal integrity issues in our designs. So
let’s start with the assumption that we DO care about signal integrity. Otherwise, there is nothing more
to talk about! Agreeing on that, let’s look at these individual rules from the standpoint of various signal
integrity issues and see when, if ever, they need be applied.
本文来自：我爱研发网(52RD.com) 详细出处：http://www.52rd.com/bbs/Detail_RD.BBS_165558_77_1_1.html] 谢谢， 学习差分了 楼主是热心人啊！谢谢！ 毛主席教导我们，好贴还是要顶一下的。谢谢lz! 没有附件。 传不上去，我编辑后发表，说我已经上传了，不让我再传了，可是附件有看不见，不知道为什么 怎么没东西 谢谢楼主 怎么会没有附件呢 楼主:可否发一份到我的邮箱谢谢!JMA@GSL.COM.HK 好贴啊，楼主太有才了 我连中文都看不懂，咋还看英文呢。 以前差分长短也没有控制的很严格
看起来还好
不过还是走齐一点好啊 【文件名】:09910@52RD_DIFFERENTIAL TRACES.pdf
【格 式】:pdf
【大 小】:3119K
【简 介】:
【目 录】:
【文件名】:09910@52RD_differential design rules.pdf
【格 式】:pdf
【大 小】:199K
【简 介】:
【目 录】:
谢谢兄弟 thank you very much! 太感谢了！！
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