CTS介绍——定义(2)

mzsm 2022-06-22 发布于湖北

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这是集成电路物理设计的第八个系列【CTS】的第二篇文章，本篇文章主要介绍CTS exception定义相关内容：

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stop pin

stop pin (sink pin/sync pin): 时钟树的一部分，cts需要对时钟树进行DRV fix同时，将sink pin进行skew banlance考虑。
告诉工具将某些pin/port识别为sink点。
>set_clock_balance_points -clock clk -consider_for_balance true -balance_point pins
sink pins examples:
A clock pin on a sequential cell, unless that cell drives a generated clock;
a clock pin on a macro cell;

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ignore pin

ignore pin (min): 时钟树的一部分，cts需要对时钟树进行DRV fix但是，不对ignore pin进行skew balance考虑。
将pin从balance对象中移除，只进行DRVd的修复。
>set_clock_balance_points -clock clk -consider_for_balance false -balance_point pins
ignore pins examples:
Source pins of clock trees in the fanout of another clock;
Nonclock input pin of sequential cells;
Multiplexer select pins;
Three-state enable pins;
Output ports;
Incorrectly defined clock pins (the clock pin does not have trigger edge information or does not have a timing arc to the output pin);
Buffer or inverter pins that are held constant by using the set_case_analysis command;
Input pin of combinational cells or integrated clock-gating cells that do not have any fanout or that do not have any enabled timing arcs.

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exclude pin

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floating pin

floating pin: 有延时信息的pin，进行skew balance 和DRV修复，和stop pin的处理方式一样，不同之处是可以在floating pin上增加或者减小一个delay值，工具在进行balance处理时，需要考虑增加或减小的delay值，从而将该pin的latency做长或者做短进行balance。
>set_clock_balance_points -clock CLK -delay -50 -balance_point [get_pins U1/CLK]