This switched: own micro-channel public number "IC design and EDA tutorial"
In the previous tweets, we introduced the form of add Checkerboard inside Placement Blockage in Narrow Channel IR-drop to solve the problem of Narrow Channel Cell inside.
IR-drop analysis and repair the problem (c): add checkerboard placement blockage in Narrow
However, there is a problem IR-drop occurs in the peripheral Macro, as shown below, appears around the region Cell IR-drop problem surrounds Macro enclosed.
This IR-drop problem occurs because presumably from three:
1, due to the Connection, Cell gathered in a large number of peripheral Macro, Cell Density relatively large;
2, since the PG Rail Macro can not pass through, the distance from the VDD Strap Macro Cell and GND Strap around are not the same, it is easy to produce IR-drop problems.
As shown below, Macro Cell left from red VDD Strap recently, IR-drop is not easy to VDD problems; but they are relatively far from the green GND Strap, so prone Ground Bounce.
Similarly, Cell Macro from the green to the right of GND Strap recently, the problem is not easy to produce Ground Bounce; but they are relatively far from the VDD Strap red, IR-drop and therefore prone to problems VDD.
Considering these two issues, we can add around Macro Halo, or become Keepout margin, do not let Cell pendulum from around the Macro too close, as shown below:
Innovus :
Add Halo command is as follows:
addHaloToBlock -allMacro 20 20 20 20 ;#给所有的Macro四边添加Halo，顺序：left bottom right top
addHaloToBlock 20 22 22 20 DTMF_INST/ARB_INST/ROM_512x16_0_INST ;#给指定的Macro四边添加Halo，顺序：left bottom right top
关于Halo的详细内容见推文：
超强整理 正在连载 - 后端布局布线工具Innovus详细教程（理论+实践+命令）
ICC2：
关于ICC2中的Keepout margin，见推文：
另外，如果Cell扎堆的情况还是比较严重的话还可以在Macro周围加上Checkerboard形式的Placement Blockage，如下图所示：
相关推文
关于IR-drop的历史文章整理如下：
IR-drop问题的分析与修复（含脚本分享）（一）：Partition boundary cells clustering
IR-drop问题的分析与修复（二）：odd pg in Narrow Channel
IR-drop问题的分析与修复（三）：add checkerboard placement blockage in Narrow
IR-drop问题的分析与修复（四）：add cell padding for cells in Narrow Channel
IR-drop问题的分析与修复（五）：Padding Clock Cells：ICC2 & Innovus