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How to derive power dissipation equation for cmos inverter?

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yuenkit

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power dissipation equation

Hi,

I need to know how to derive the equation for
switching power & energy of cmos inverter.

When I search this topic from the web, some give the equation
P = fxCV²

Some other give
P = ½ f x CV²

And also, for the energy, how to derive it?

when the signal goes hi, the capacitor is charging, when signal goes low, it is discharging. How does this take into account in P and E calculation? Is there any negative value as the direction of electron flow change?

for Energy and Power, is it measure when the transition taking place, or depend on how long the state maintain?
if it measure by considering transition, what edge it considering? rise transition or fall transition? or both?

Thank you.
 

power dissipation in cmos

power disspation for any circuit is given as Pd =0.69RC, am i rgt?????


correct me if i am wrong, u can find the derivation of this anywhere, if u didnt find then let me know.


thanks,
Prasad
 

mathematical equation to model delay in mos

I believe the equation you give is for sinusoidal AC power
Pd =0.69RC

I need the power equation for IC design power. :)

Another thing, does any one know, will the transition time affect switching power dissipation?
 

cmos power dissipation formula

that was told by Prof. Rabeay while mentioning Pd for digital ciruit, is that onlly for sinusoidal signal????????


let me know if u know anything more on that???

thanks,
Prasad

Added after 13 minutes:

that eq is valid for any ciruit including cmos inverter " this was told by Prof. Rabeay , as any ckt can be broken down to R and C ....


if u know anything more on that let me know...
thanks,
Prasad
 

power dissipation cmos

ok,

this is what i know.
R doesn't play a major rule in power dissipation in cmos.
It only affect te propagation delay, the RC constant

from the equation
e = cv²
p = cv²f
this is all the power dissipating in one period.

for
e = ½cv², this is energy for each toggle, either from 0 to 1 or 1 to 0.
so for one clock cycle, it has 2 toggle, so the e= cv².
 

cmos power equation

yuenkit said:
Another thing, does any one know, will the transition time affect switching power dissipation?
Click to expand...

Of course the transition time is affecting the switching power dissipation. The longer transition time, the longer time the inverter has both transistors opened, permittting the current to flow from the power supply
to ground.
If the inverter doesn't drive a long line (small RC), the power it consumes cames mainly from this crowbar current. This current is also depending on process corner, and temperature.
Why not simulate a parasitic extracted inverter? Can you trust such a calculation today?
 

crowbar current in cmos inverter

actually there are 3 main contributors for power dissipation.they are: switching current,short circuit and leakage & subthreshold current. the equation given corresponds only to switching current .other 2 factors are not taken care of.

just try following link , u will get some req info

**broken link removed**
 

Re: How to derive power dissipation equation for cmos invert

For switching power, it makes sense to exclude leakage power. Moreover, it may be advisable to subtract the load power while calculating the switching power and energy. To summarize, one must account for only the power dissipation only due to crowbar current for switching power calculations.
 

Re: How to derive power dissipation equation for cmos invert

Sorry for the confusing terminology used. The explanation I provided is true for internal power and not switching power. As I understand, switching power is the power consumed by the load and other interconnect capacitances during switching. Internal power is the power mainly consumed within the cell and includes the crowbar current.
 

Re: power dissipation equation

Hi,
what is the Mathematical Prerequisite to understand power dissipation derivation(Not the final equation).Some I knew are integration, differentiation. Also if you have any material for both(Derivation and Mathematical Prerequisite) please share.

Thanks in advance
Regards,
N.Raghavan
 

Of course, the transition time of impact on the switching losses of power. The longer the transition time has more time for the two transistor drive open permittting flows from the output current
Mass.
If you do not control the player by a long series (small RC), is the power that is consumed, in particular the crowbar current. This current also depends on angle of the process, and the temperature.
Why not simulate an inverter won parasite? You can count on that calculation today?
 

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