[time-nuts] Gate propagation delay jitter

SAIDJACK at aol.com SAIDJACK at aol.com
Tue Apr 10 19:50:45 EDT 2007


 
In a message dated 4/10/2007 14:33:17 Pacific Daylight Time,  
bruce.griffiths at xtra.co.nz writes:

Yes  ground bounce can play havoc with the effective switching thresholds.
One  would expect this effect to be much worse with single ended  clocks.

Bruce



Hi Bruce,
 
not to give away too much, but in our Jackson-Labs Fury GPSDO we  compensate 
for VDD bounce as well by having fully-differential circuits with  special 
current balancing circuitry.
 
Thus not only do clocks have to be differential, but every output of the  
circuit should be differential as well to balance the VDD currents.
 
This helps prevent feeding noise into the VDD rails, which can show up at  
other IC's. We were able to completely get rid of spurs in our phase noise  
measurements with this technique.
 
bye,
Said 



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