Hi, but when I also add the term (1+λVds) to the current equation and have fixed the current Id, Vt and Kp, how can I understand the values of Vgs and Vds? For example, in the current mirror I want polarization with a fixed Id current, how can I also fix the Vds in such a way as to obtain the fixed Vgs? Could you point me to a guide that explains how to make a MOSFET work as an ideal current generator to impart a reference current into a current mirror? thank you so much
Also, are you able to extract additional parasitics from the datasheet to further enhance the model? Looking at some SPICE models, they are significantly more complicated.
Hi, really useful video, many thanks for it. One question came to my mind regarding with the Id, Vds map: why do we need to use the one for Tc 150°C, instead the other for 25°C? Thanks.
Hi Robert, I have a question about the formula for Kp. Why "W" and "L" are not in the formula for Kp? I understand that they are not involved in the formula for Vt, but when you plug the expression for Vt into the expression for Kp, "W" and "L" will still be there. Actually, "WKp/L" can be regarded as a lumped parameter. How can I calculate Kp without using the value of "W" and "L"? Could you explain that? Thank you.
+Minyu Cai Hi Minyu, in SPICE, the default W and L are both 100uA so in turn W and L cancel out. If you know what W and L are, you get the results that you get from the equation and then solve to the actual KP. Hope that helps
how did you calculated the gm? i mean how did you find from the datashhet tha Ioperate ? because i want to find the maximum frequency of the transistor , your formula gives Cgs and Cgd but you do not tell how to find the gm . (Ft=gm/2pi(Cgs+Cgd)
+ramu B In the triode region of operation, the Mosfet looks like a resistor. In the saturation, an ideal Mosfet is suppose to operate like an ideal current source, meaning that the current source impedance in infinite. However, in practice, the Mosfet act in the saturation mode like a current source in parallel with a resistor. This output resistor is sometimes refered to as ro. In addition, lambda is a spice parameter that models the slope or the ro of the spice model. Lambda is what give the Mosfet curve is slope. I hope this makes sense. Questions and comments can be sent to rbola35618@aol.com
Hi, how about the function that describes the intrinsec Capacitances?, These capacitances changes in terms of the Vds voltage, so the parameters you add of Ciss, Coss, etc ... are fixed ?
Hi Diego, you are correct. The Cds capacitance changes as Cds changes. When Ciss, Coss and Crss, these are fixes and I don't think they chance. Keep in mind that this is a first order approximation. If you want a more complete model, please email me at rbola35618@aol.com and I can send you a Mathcad file. However, this file you need to need the process parameters of your mosfets. I file that I have is for the MOSIS 0.5 AMIS process.
Hi 08Ultrasonic, Email me at rbola35618@aol.com and I will email you the Mathcad script and a PDF file of the equations. The other parasitics that you can extract is the Cgs and Cgd which effect the frequency response and speed of the MOSFET.
Thanks for the video, and mad props for using Windows 95 in 2013
1. This is Windows 7.
2. Mad props for admitting your birth date is in the 2000s which means you belong to the dumbest generation in history.
Thank you for your big effort. One of your many great, clearly explained videos. God bless you
You are very welcome
Hi Robert! Great, you came up with it.
Yes, thanks
I just used your Mathcad approach. Very nice.
Your Mathcad equation for VT has a mysterious V in the denominator.
This cancels the "V" used to represent the unit in the output
Great video! I really appreciate this a lot.
Hi, but when I also add the term (1+λVds) to the current equation and have fixed the current Id, Vt and Kp, how can I understand the values of Vgs and Vds? For example, in the current mirror I want polarization with a fixed Id current, how can I also fix the Vds in such a way as to obtain the fixed Vgs? Could you point me to a guide that explains how to make a MOSFET work as an ideal current generator to impart a reference current into a current mirror? thank you so much
Also, are you able to extract additional parasitics from the datasheet to further enhance the model? Looking at some SPICE models, they are significantly more complicated.
thank you, very useful video, I learned a lot!
I am glad you liked it. Robert
Hi, really useful video, many thanks for it. One question came to my mind regarding with the Id, Vds map: why do we need to use the one for Tc 150°C, instead the other for 25°C?
Thanks.
Because never, ever, does a semiconductor run at 25°C or below without liquid cooling.
Hi Robert,
I have a question about the formula for Kp. Why "W" and "L" are not in the formula for Kp? I understand that they are not involved in the formula for Vt, but when you plug the expression for Vt into the expression for Kp, "W" and "L" will still be there. Actually, "WKp/L" can be regarded as a lumped parameter. How can I calculate Kp without using the value of "W" and "L"? Could you explain that? Thank you.
+Minyu Cai Hi Minyu, in SPICE, the default W and L are both 100uA so in turn W and L cancel out. If you know what W and L are, you get the results that you get from the equation and then solve to the actual KP. Hope that helps
+Robert Bolanos (Maverick Volleyball SA) Thank you, Robert. It does help.
thanks the eq2 helped me
Hi, you can model both conditions
Thank you for the great video. Do you know of a way to model igbts from datasheet ?
The model works for the saturation region but is not valid for the triode region. Mosfet level one models don't work well for power mosfets
Yes. This is my doubt. This might not work for a power mosfet as it is operating in active region.
Thanks a lot!
You are welcomed!
Finally I can apply them :D
Hi, Where did you obtain the initial equations from for this conversion?
how did you calculated the gm? i mean how did you find from the datashhet tha Ioperate ? because i want to find the maximum frequency of the transistor , your formula gives Cgs and Cgd but you do not tell how to find the gm . (Ft=gm/2pi(Cgs+Cgd)
very interesting thank you
I am not able to understand how you read the scale 600mA at the timeline 8:00, is it a logarithmic scale?
Hi Isac, good question, yes, the graph is logarithmic. 😀
Hi Robert,
can I write a code with those formulas (Not just changing parameter values) in SPICE?
mak hos Well all math can be made into a code
It just depends on how good you are at interpreting maths.
Hi Robert..what is the significance of LAMBDA in the simulation?
+ramu B In the triode region of operation, the Mosfet looks like a resistor. In the saturation, an ideal Mosfet is suppose to operate like an ideal current source, meaning that the current source impedance in infinite. However, in practice, the Mosfet act in the saturation mode like a current source in parallel with a resistor. This output resistor is sometimes refered to as ro. In addition, lambda is a spice parameter that models the slope or the ro of the spice model. Lambda is what give the Mosfet curve is slope. I hope this makes sense. Questions and comments can be sent to rbola35618@aol.com
Hi, how about the function that describes the intrinsec Capacitances?, These capacitances changes in terms of the Vds voltage, so the parameters you add of Ciss, Coss, etc ... are fixed ?
Hi Diego, you are correct. The Cds capacitance changes as Cds changes. When Ciss, Coss and Crss, these are fixes and I don't think they chance. Keep in mind that this is a first order approximation. If you want a more complete model, please email me at rbola35618@aol.com and I can send you a Mathcad file. However, this file you need to need the process parameters of your mosfets. I file that I have is for the MOSIS 0.5 AMIS process.
typographical error in the formula for Vt..
Hi 08Ultrasonic,
Email me at rbola35618@aol.com and I will email you the Mathcad script and a PDF file of the equations.
The other parasitics that you can extract is the Cgs and Cgd which effect the frequency response and speed of the MOSFET.