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power dissipation plot

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cfreng2

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Hi all,

Can anyone tell me how to plot the power dissipation of an inverter with respect to the frequency?
 

I think you mean switching frequency or is it a tri state inverter with a clock in it? Power dissipation increases with increase in switching frequency. If its switching frequency you can probably alternate the input for a different simulation times in the hspice netlist and measure the power for each simulation.

Provide a input to the inverter with alternating 10101010. Specify the times when it has to be one and when it has to zero. Measure the power.

Do the same by altering the frequency at which inverter input changes ie the times at which the 1 and 0 occurs and calculate the power at each iteration and plot the graph.

-Aravind
 

What you are asking is a bit more complicated because in mission mode the inverter may not switch every time, so you need to have an actual switching activity along with the actual time the inverter is high, then you can determine the power dissipation. This is why statistical analysis of power is much better.
 

Do you know how to do that in HSPICE? I already have the circuit for a fan out of 4 inverter chain. All i need is to plot the power dissipation versus the frequency.
 

If you want to use HSpice then what was suggested before will work, but it will not give you the actual power in mission mode, only the characterized power for a certain toggle rate.
 

cfreng2 said:
Do you know how to do that in HSPICE? I already have the circuit for a fan out of 4 inverter chain. All i need is to plot the power dissipation versus the frequency.


I have the same question but the tools used for simulation are eldo with easywave
 

@cfreng2

You need to give the input as a piecewise linear wave.

This is a sample hspice file:
.include "your library name"
.include lvstest.sp $ you should put your output file from extracion here

.option post
xi in out / inv $ Call your system to simulate. put I/O info first and then ends with subckt name

vdd! vdd! gnd 1.2V $ Your VDD voltage value
Vin in gnd (0ns 1.2V 1.1ns 1.2V 1.2ns 0V 2.3ns 0V 2.4ns 1.2V...........) $ How input varies during simulation
Cout_b out 0 20f $ output load
.tr 0.01ns 4ns $ simulation step and simulation time
.measure tran avg_power avg power from 0n to 240n
.end

You might have to do some research regarding the spice file for various commands. But there are plenty of tutorials available on UNIVERSITY websites to help you out. But this spice file should help you to start off.

This is the format

PWL (T1 V1 T2 V2 T3 V3 ... Tn Vn ... )

Eg:

vin a gnd (0ns 1.2V 1.1ns 1.2V 1.2ns 0V 2.3ns 0V 2.4ns 1.2V...........)

Hopefully this helps.

-Aravind
 

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