How to calculate the RC oscillator power

[kevinwang123]

Who can tell me how to calculate RC oscillator power?

thanks and best regards!

 

[Btrend]

assumption: simple R+C oscillator, constant input voltage Vin, oscillator period=T
power : P=(1/T)*∫i(t)*V(t)dt=(Vin/T)*∫i(t)dt ---(0)
i(t)=(Vin-Vc)/R, ---- (1)
Vc(t)=Vin[1-exp(-t/τ)], τ=1/(R*C), --- (2)
from (1) and (2),
i(t)=Vin*exp(-t/τ)/R ---- (3)

from (3) & (0)
P=(Vin/T)*∫Vin*exp(-t/τ)/Rdt =(Vin²/R)*(1/T))*∫exp(-t/τ)dt
=(Vin²/R)*(τ/T)*(1-exp(-T/τ))

if T=10τ, P≈(Vin²/R)*0.1
if T=2τ, P≈(Vin²/R)*0.43

 

[sunking]

test the average current
P=UI

 

[kevinwang123]

thanks all of you!
Could i calculate average current for several period time by integrator or maybe a
long time?

 

[sunking]

Add an amperemeter in the circuit
Or if simulate, add a small resistor(1m Ohm) and test the current

 

[kevinwang123]

if i add a amperometer or 1 ohm resistor,i only get the square wave current,which
is discontinuity. Should i still integrate it?

thanks a lot!

 

[marshel]

in cadence's design enviiroment I just measure the VDC's current and voltage
then use the calculator to get the average IV value.