芯片ECO(一）

1、ECO flowECO通常包含timing ECO，function ECO，我们本节看看timing ECO。timing ECO通常先将PD设计加载到tempus进行timing signoff分析，通过eco_opt_design等命令fix remaining timing violations，并产生ECO脚本，在innovus中执行ECO脚本后，QRC提取寄生参数， 再次进行tempus时序分析。

2、ECO目标

• Hold timing
• Setup timing
• Design Rule (max_cap/max_tran)
• SI violations (SI Slew, SI Xtalk and SI Glitch)
• Reduces Power and Area:

1. Area reduction
2. Leakage power reduction
3. Dynamic power reduction
4. Leakage and dynamic power reduction concurrently

3、ECO方法

• cell swapping
• cell resizing
• buffer/inverter insertion and deletion

4、ECO脚本

batch mode下，tempus的ECO Timing DB文件可以通过eco_opt_design命令自动生成，脚本如下：-

<pre class="code-snippet__js" data-lang="properties">```
<span class="code-snippet_outer"><span class="code-snippet__attr">read_lib</span> <span class="code-snippet__string">$liberty</span></span>
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read_lib -lef $lef

<span class="code-snippet_outer"><span class="code-snippet__attr">read_verilog</span> <span class="code-snippet__string">$netlist</span></span>
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set_top_module my_top

<span class="code-snippet_outer"><span class="code-snippet__attr">source</span> <span class="code-snippet__string">viewDefinition.tcl</span></span>
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read_def $def_file

<span class="code-snippet_outer"><span class="code-snippet__attr">source</span> <span class="code-snippet__string">spef.tcl</span></span>
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set_distribute_host -local

<span class="code-snippet_outer"><span class="code-snippet__attr">set_multi_cpu_usage</span> <span class="code-snippet__string">-localCpu 8 -remoteHost 2 -cpuPerRemoteHost 4</span></span>
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eco_opt_design -hold

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在芯片规模较小时，analysis view少于8个时，我们可以自己生成ECO Timing DB，然后在single Tempus session下逐个完成timing ECO。

<pre class="code-snippet__js" data-lang="properties">```
<span class="code-snippet_outer"><span class="code-snippet__attr">read_lib</span> <span class="code-snippet__string">$liberty</span></span>
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read_lib -lef $lef

<span class="code-snippet_outer"><span class="code-snippet__attr">read_verilog</span> <span class="code-snippet__string">$netlist</span></span>
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set_top_module my_top

<span class="code-snippet_outer"><span class="code-snippet__attr">source</span> <span class="code-snippet__string">viewDefinition.tcl</span></span>
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read_def $def_file

<span class="code-snippet_outer"><span class="code-snippet__attr">source</span> <span class="code-snippet__string">spef.tcl</span></span>
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set_distribute_host -local

<span class="code-snippet_outer"><span class="code-snippet__attr">set_multi_cpu_usage</span> <span class="code-snippet__string">-localCpu 8</span></span>
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#注意，下面先保存的ECO Timing DB: myEcoTimingDB

<span class="code-snippet_outer"><span class="code-snippet__attr">set_eco_opt_mode</span> <span class="code-snippet__string">-save_eco_opt_db myEcoTimingDB</span></span>
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write_eco_opt_db

<span class="code-snippet_outer"><span class="code-snippet__attr">set_eco_opt_mode</span> <span class="code-snippet__string">-load_eco_opt_db myEcoTimingDB</span></span>
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eco_opt_design -hold

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完成timing ECO后，在tempus工作目录下会生成eco_innouvs.tcl脚本用于innovus完成增量ECO布局布线。
若innovus eco route后有较多DCR violation，可以通过ecoRoute -fixDrc来修复,不一定能100%修好，部分可能需要手动修复。

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转载：全栈芯片工程师