<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">差分信号的规则可以在电气规则下面建立，也可以在物理规则下面建立；电气规则下建立的差分信号规则是全局性的，不受区域规则的约束，在BGA等需要密集出线的地方难以满足要求，所以差分信号一般都是在物理规则下面建立的。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">一、在电气规则下建立差分信号规则，首先点击左边的工作选择区中的Electrical工作表下的Electrical constraint set→Routing→Differential pair,然后选择菜单命令Objects→Create→Electrical set，如图下图所示：<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">弹出Create Electrical set对话框。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">在 Electrical CSet编辑框输入差分信号规则名称，这时在右边的工作表中可以看到多了一个DIFF_DQS的约束规则，如下图所示：<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">差分信号的约束规则参数主要有以下几个：<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Uncoupled Length：差分信号网络中不匹配中的长度，即不能按差分信号
走线的总长度。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Min Line Spacing：最小的线间距。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Primary Gap：差分信号最优先选择的线间距。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Primary Width：差分信号最优先选择的线宽。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Neck Gap：差分信号在 NECK 模式下的线间距（用于在
布线比较密集的区域）。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">Neck Width：差分信号在 NECK 模式下的线宽。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">设置好差分信号约束规则后，将该约束规则应用于差分信号上，点击左边的工作表选择区中的Electrical 工作表下的 Net 下Routing,在右边的工作表找到所建的差分信号，在 Referenced Electrical CSet 选择刚才设置好的差分信号约束规则 DIFF_DQS，如下图所示：<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">这样就把设置好的差分规则分配到对应的差分网络了。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">二、在物理规则Physical Constraint Set下建立差分信号规则。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">弹出命名对话框如下：<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">
<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">根据需要设定各个参数的数值并把规则赋予需要的网络，操作方式与电气规则下建立差分信号规则类似。<p hiragino="" sans="" gb",="" "microsoft="" yahei",="" simsun;="" vertical-align:="" baseline;="" word-break:="" break-word;="" color:="" rgb(93,="" 93,="" 93);="" white-space:="" normal;="" background-color:="" rgb(255,="" 255,="" 255);"="" style="margin-top: 1em; padding: 0px; font-family: "Microsoft YaHei"; background-color: rgb(244, 244, 244); border: 0px; font-variant-numeric: inherit; font-stretch: inherit; font-size: 18px; line-height: inherit;">以上便是
PCB设计中差分信号的规则设置，
