There is a desire to move current state-of-the-art niobium Josephson IC fab
rication processes (similar to3 mum) to smaller sub-micron linewidths in or
der to realize a decrease in gate size and increase in both speed and packi
ng density. However, cost and time dictates that a way be found to reuse th
e existing RSFQ gate/cell development that has been done at the 3-mum level
. Cell retargeting is the process of migrating existing designs to a new te
chnology, with the effort focused on the maximum reuse of existing material
. We have investigated a number of issues critical to this process, includi
ng both the physical and electrical aspects. Comments are made on methodolo
gies for RSFQ cell retargeting with respect to existing reduced-linewidth J
J fabrication processes. Experimental demonstrations are shown for retarget
ed RSFQ static digital frequency dividers (toggle flip-flops) operating at
220 GHz, 240 GHz, and 395 GHz.