In Multi Voltage VLSI Design, isolation cells play an important role in the modern VLSI world. Requirement : Lets have a look at the below diagram - - Lets assume VDDA voltage domain is always ON and VDDB voltage domain can go ON or OFF based on the certain design requirements ( To minimize the power consumption of the whole design) - When VDDB domain is OFF , the outputs of all the gates of this domain are at unpredictable state. - Since , some of the gates of VDDB domain might be driving some logic in VDDA domain (Which is always ON) but since VDDB domain signals are at unknown state (X) and they might corrupt the logic in VDDA domain and eventually the VDDA domain functionality gets corrupted - To avoid such scenario , we need to isolate the signals going from VDDB(OFF) to VDDA(ON) domain by the use of nothing but called as isolation cells - By using isolation cells we will clamp the respective logic to a proper value (0 or 1 or Latch ) Isolation cell...
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