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substrate terminal - RF Cafe Forums
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dipak
Post subject: substrate terminal Posted: Mon Dec 18, 2006
8:10 am
Captain
Joined: Tue Nov 14, 2006 7:21 pm
Posts:
9
Location: Nagpur(M.S)
what should be the effects if we dont
connect substrate terminal to the ground in CMOS process?
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fred47
Post subject: SubstratePosted: Mon Dec 18,
2006 12:33 pm
General
Joined: Wed Feb 22, 2006 3:51
pm
Posts: 104
Hi Dipak!
Not connecting the substrate to
ground in a CMOS process would have differing results, depending on
what it is connected to:
1. Nothing. A floating substrate will
cause roughly one-half of the mosfets to operate improperly. Which half
would depend on whether your process was N-well or P-well. (As an aside:
when I covered for a professor during a sabbatical, I was able to watch
the students try to find out why their labs weren't working - a lot
of very strange effects showed up due to an open substrate connection.
2. Negative voltage (for a normally-powered chip): Unless Vdd(max)
is exceeded, you'll only encounter problems if the substrate is inadequately
bypassed.
3. Positive voltage: depending on the voltage, as you
increase from 0 volts, you'll increasingly move away from proper operation
until your design doesn't work.
Good Luck!
Fred
Posted 11/12/2012 |
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