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cmos nor2 static power (Read 4177 times)
Darock
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cmos nor2 static power
Jul 29th, 2010, 12:31pm
 
Hi all,

I have a question regarding static power calculation for a or2 gate.
Let say that A,B = 0 and only subthreshold leakage is observed.

regarding the attach schematic, can i write :

I_t1 = PMOS sat= µ.Cox.(W1/2L) (Vsg + Vt)2
I_t2 = PMOS sat= µ.Cox.(W2/2L) (Vsg + Vt)2
I_t3 = NMOS sub= µ.Cox.(W3/L) Vt2 e((Vgs-Vth)/nVt)
I_t4 = NMOS sub= µ.Cox.(W4/L) Vt2 e((Vgs-Vth)/nVt)
I_t5 = PMOS sub=µ.Cox.(W5/L) Vt2 e((Vgs-Vth)/nVt)
I_t6 = NMOS sat= µ.Cox.(W6/2L) (Vgs - Vt)2

Please let me know if you think that these equation are correct,
and also i m not sure about the way to add them.

do i have to add them all to find the static power ?

thank you for your time,

David.



ps : Let me know if you have an example of this kind of calculation
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« Last Edit: Jul 29th, 2010, 2:12pm by Darock »  
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rfcooltools.com
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Re: cmos nor2 static power
Reply #1 - Aug 6th, 2010, 6:48pm
 
Darock,

To simplify you can approximate all trioded (not saturated) drain voltages as equivalent to their supply or ground respectively. The reason is that the subthresold current will be small and the I*R drop will be negligible.  Second you can assume T3 and T4 to be the single device with  the combined  width.   Third you will need the subthreshold equation with Vds included.
Finally for the subthreshold devices
|VDS|= vsupply
VGS=0

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