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What does clock feedthrough mean?

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prasadel06

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hi..
what is meant by clock feedthrough.....
how reduce that...
thanss
 

lakshman.ar

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what is clock feedthrough

clock feed through concept is applicable wen u do design partition.

assume u have 2-3 partitions in ur design and now if the clk for the second partition hs to go thru the first partition, then the tool doesnt know which is the source or root pin of the clk for the second partition, then u need to specify the clock as a "feed thru" clock in the first partition !

i,e in effect, instead of the clk directly goin thru to the 2nd partition, the 1st partition now feeds the clk thru ( goes thru) to the 2nd one.

If there is no other go, then feed thru option is the one. Else re-do the design partition such tht the clock is not fed- thru the 1st partition to the 2nd one !!!

PS:
CDU - clock distribution unit is placed such tht the clk for the second partition has to go thru the one or more partitions in the design

WBR
Lakshman
 

prasadel06

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clock feed through

hi laxman.....
thank you for reply....
but i am not getting...actually in my project.....
i am using clocked xnor by using cmos, with clock i am getting spikes in stable state i.e when the clock applied.... hoe to reduce that spikes...
 

carv_13

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what is clock feed through

Don't know if this will work but you can try to pass the clock signal through a couple of inverters. This could give you a clock which doesn not have spikes. Its just a suggestion and I haven't tried it out. You can give it a shot.
 

lakshman.ar

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clock feedthrough

@ prasadel06
ohhhh .... ok !!!
u meant to say u are gating the clock thru a Xnor gate is it ???. can u pleas tell me with wat signal are you trying to gate the clk with ?

u mite be getting the glitches in the clk, due to the other signal tht u are gating the clk with !!

can u pls tell me from which logic/block is the other signal to the XNOR gare comming from ??

cos with tht, we may get a solution !! !
WBR
Lakshman
 

shiv_emf

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what is clock feedthrough

feedthrough and glitches !

Glitches r usually observed due to combinational logic... plz check it...

is it static or dynamic glitch ?
 

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