How do i get the capacitance value using AC analysis ? Anyone can help ?

 

Welcome to AAC!
Why do you want to measure Cgs? The value (5.2n for the FET shown) is specified in the model.

 

Welcome to AAC!
Why do you want to measure Cgs? The value (5.2n for the FET shown) is specified in the model.

Hi, how do you get that ?
Actually i need to get all that so that i can calculate input capacitance and so on.
To compare with the datasheet. I use the formula stated on my .asc
I'm not sure whether that circuit is the right configuration to measure parasitic capacitance.

 

how do you get that ?

Right-click on the FET symbol, left-click on "Pick New MOSFET", read the .model text to the right of the device name.

To compare with the datasheet

Many (most/all?) Spice models are based on the device datasheets, so simulation would yield the datasheet values. You'd be going round in circles.

 

Right-click on the FET symbol, left-click on "Pick New MOSFET", read the .model text to the right of the device name.

Many (most/all?) Spice models are based on the device datasheets, so simulation would yield the datasheet values. You'd be going round in circles.

How about this one ? I use the spice lib from renesas. I create new symbol etc and need to run simulation to compare with the datasheet.
Does it also the same case ? I use plot .step'ed .meas data function to plot the graph. But not sure on how to read the information.

 

Hi.
I have long found a way to solve your problems.
The clever man did it. Who did this look at the electronic scheme.

 

Hi.
I have long found a way to solve your problems.
The clever man did it. Who did this look at the electronic scheme.
View attachment 134892

View attachment 134893

wow ! thank you so much ! I will study this first

 

Btw, do you know how to use .meas statement to find the value of capacitance at Vce=25V ?
I try to use this equation but failed to measure it.

.meas Cies FIND V(cies) WHEN V(Vce)=25

Is it because it mixed up between AC and DC ?
Before this it worked just fine for other measurements.

 

Btw, do you know how to use .meas statement to find the value of capacitance at Vce=25V ?
I try to use this equation but failed to measure it.

.meas Cies FIND V(cies) WHEN V(Vce)=25

Is it because it mixed up between AC and DC ?
Before this it worked just fine for other measurements