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Johnson counter vs grey counter in syncronisation/clock divide logic

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dll_fpga

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Both johnson counter and grey counter has 1 bit change .
Which do we prefer for synchronizers? and which one for clock dividers?
 

dll_fpga

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Grey counters are used for synchronisation purpose.

hi sakthi,
I could see a design,where johson counter is used as the clock divider? Does it offer any advantages...I could only find that johnson counter also has 1 bit change between the count sequences...
 

qieda

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Hi,

I think johnson counter are used for clock dividing, because they are faster, because we do not need much logic for this. At least compared to a binary counter.
e.g. for dividing by four you just need 2 FF and an inverter. If the FF would have an inverting output you do only need the two FF and loop the output of one FF to the input of the other FF.


regards
 
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