how to find average leakage power and lcircuit capacitance at output???

[jalananup]

Hi everyone!

I am facing a problem while analyzing my digital circuits. I am not able to calculate the average leakage power of the circuit and the capacitance at the output.

Does anybody know the answer?? I would be very obliged...thankyou in anticipation..

 

[jgruszynski]

Average leakage power is related to Idd and Iddq parameters - either simulated or measured (better). Google the these terms.

Capacitance seen by the output is your load which is application dependent. There is typically a maximum load capacitance defined for any given logic family or specific IC device.

 

[jalananup]

hey, i am using Cadence Spectre to simulate my Multiplexers, I am not able to find out the average leakage power(simulated) of the simple 2:1 MUX circuit implemented using CMOS. Also, i want to find out the load capacitor(simulated) as well. If u can plz. help me out...

 

[jgruszynski]

Don't know specifically how set up it up in Cadence, but if you are using a SPICE-like circuit simulator, it should be just a matter of reading off the Vdd current. Otherwise I'd assume in a pure digital simulator of modern vintage that this would be an option of any simulation. An opportunity for RTFM.

For the capacitance, again, that's application dependent. To figure out the drive capacity (the upper bound for load capacitance), analyze and create a Thevenin model for the output circuit (its output impedance), define the frequency performance you want, assume a pure capacitive load, and solve the RC time constant for C.

These should be pretty obvious.