[SOLVED] Is there a need to define gated_clock?

[irun2]

Let's say a clock source is defined and it has to pass through a gating cell, Does the output the the gating cell need to be defined as generated clock?

 

[sharif.shiek]

tool will implicitly define generated clocks and we can also explicitly specify generated clocks..but we have to check that whether the master clock is specified correctly or not

 

[jbeniston]

No, you don't need to, unless you are using the gating cell to lower the frequency, in which case there may be some benefit in defining a generated clock.

 

[sharif.shiek]

yaa..main reason behind specifying generated clocks is, "by default CTS will not balance skew for exclude pins..so if we not specify the generated clocks, then tools treats that as exclude pin, and will not try to balance the skew"

 

[jbeniston]

yaa..main reason behind specifying generated clocks is, "by default CTS will not balance skew for exclude pins..so if we not specify the generated clocks, then tools treats that as exclude pin, and will not try to balance the skew"

This can't be correct. Think of of the automatic clock gating that is inserted by power compiler or RTL Compiler. You don't generated clocks added for those.

 

[sharif.shiek]

ya ok..thank you for giving clarification

---------- Post added at 12:56 ---------- Previous post was at 12:45 ----------

hey...i think there is no need to assign output as generated clock..because in case of gating, there will be no modifications in source clock(say frequency, phase) and mainly gated clock concept is to reduce the power consumption, and we are not generating any new clock source, so no need to assign a gated clock as generated clock