LTspice tutorial - FREQ function
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- Опубліковано 21 лип 2024
- #195 In this video I look at the FREQ function that can be used in LTspice to insert tables of frequency dependent complex numbers. Its not very well know function, since the help file does not really mention it, but its a very usefull tool in modeling Sparamters or other frequency dependent complex impedances.
Further reading:
designers-guide.org/forum/Att...
S1P file of analyzed component:
drive.google.com/file/d/1o21-...
LTspice Tutorial series:
EP1-Getting started:
• LTSpice Tutorial - EP1...
EP2-AC simulation and the Baxandall tone control circuit:
• LTspice tutorial - EP2...
EP3-.param and .step directives:
• LTspice tutorial - EP3...
EP4-How to import libraries and component models: • LTspice tutorial - EP4...
Ep5- Stock example simulations to play with: • LTspice tutorial - Ep5...
Ep6- Basics of FFT analysis and .four statment: • LTspice tutorial - Ep6...
EP7- Dependent voltage and current sources
• LTspice tutorial - Ep7...
Ep8- Turning a datasheet into a component model
• LTspice tutorial - Ep8...
EP9- Independent voltage and current sources
• LTspice tutorial - Ep9...
Ep10- .wave statement and audio file processing
• LTspice tutorial - Ep1...
Ep11 The effect of temperature on your circuit
• LTspice tutorial - The...
EP12 Modeling a DC brushed motor
• LTSpice Tutorial - Mod...
Ep13- Worst Case, Monte Carlo and Gaussian statistics circuit analysis
• LTspice tutorial - Wor...
EP14 - Digital circuits and logic gates • LTspice tutorial - Dig...
EP15- SMPS EMI and electrical noise and filters
• LTspice tutorial - SMP...
EP16- Feedback loop simulation
• LTspice tutorial - Fee...
Ep17 - Verifying Simulation Models
• LTspice tutorial - Sim...
Ep18 - Simulating Capacitors
• LTspice tutorial - Sim...
Ep 19 - Simulating Inductors
• LTspice tutorial - Sim...
EP 20 - Noise simulations
• LTspice tutorial - Noi...
Ep21 - Models and Libraries
• LTspice Tutorial - Cre...
Ep22- Voltage and current limited source
• LTspice Tutorial - Vol...
Ep23- Measuring Power Factor
• LTspice tutorial - Mea...
Ep24 - Modeling a vacuum tube triode
• LTspice tutorial - Mod...
Ep25- Using standard symbols
• LTspice tutorial - Re-...
Ep26- Modeling transformers
• LTspice tutorial - Mod...
Ep27 - Stepping sets of parameters
• LTspice tutorial - Ste...
EP28 - Simulating Quartz crystals
• Measuring and Simulati...
Ep29 - Simulating gas discharge tubes
• LTspice tutorial - Gas...
Ep30 - LT tips and tricks
• Video
Ep31 - Modeling switches
• LTspice tutorial - Mod...
EP32 - FREQ function
• LTspice tutorial - FRE...
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These are the BEST LTspice tutorials I found so far. Thank you very much
Good presentation! Congrats!
Very nice video!!! Thank you for sharing your knowledge. If I had one wish free I would love to see an in detail explanation how the model at 10:46 works and if there are other modeling possibilities. Nevertheless very nice so thank you!
I'll have to study that part in a bit more detail before I can do a proper explanation :D anyway, in case you need it, I left a document in the video description that highlights the circuit for the 2 port Sparameter models as well.
Awesome ! Thanks. Is the STL file for the VNA support somewhere plz ?
So, it's like PWL but in the frequency domain...
Great job, you should help write the LTspice manual, 😅
My brother , I need your help. I am currently working on a graduate project to operate a water pump through direct solar panels, and you know that the voltage will change a lot. My design is to build a DC to DC converter. The voltage range between 100 volts in the morning and evening to 350 volts at noon. can it works in this large range of wide range of voltage without getting core saturated or losing his job ,Do u think by changing switching freq and duty cycle can it work fine?.Arduino nano as switching frequency will be
Very nice tutorial. I really learned something useful, thanks.
To convert S11 file to simulation model, a python script, may be ?
That certainly is a possibility, although its not something I personally know how to do :D
What a Great Tutorial! Could you give us the VNA lib? in order we can also simulate the component you measured, please. Cheers from Brazil
I added it into the description.
A real signal such as a sound wave is AC in nature and its mathematical signal representation is expressed as a a sinusoid.My question is how a varyring DC signal from DC temperature sensor signal and its mathematical signal representation is expressed?How does its waveform differ from AC signal sunusoid and do we analyse DC varying signal?
DC by definition is constant; if there is any variation, however slow (like the temperature signal) it becomes AC; now in real life, every signal could be considered AC, but at some point you make the assumption that it isn't just to make the analysis easy. You can also perform an analysis over a short period of time over which the signal is actually constant, and thus perform multiple analysis of "DC signals" to observe the long term AC behaviour.
For the purpose of mathematical analysis, you can decompose a signal into an AC and DC component - for ex the 5V of a switching converter has a DC of 5V and an AC ripple of 100mV (as example).
Thanks for this information. I noticed a flow in this. When i model frequency dependent resistor in ltspice, it works well in AC analysis. But its not working in time domain. E.g performance on a square wave. Am I missing something?
No, you did not miss anything... but I think I mentioned this - the Freq function will only work for AC simulations..
Hello. Do you have any experience with ngspice/ Berkeley spice?
As it goes with FOSS, ngspice is certainly most advanced and permissive but less intuitive and easy to use than the LTspice freeware. Though ngspice has a complete documentation and Qucs-S and Kicad provide nice alternative GUI.
Hello, @FesZElectronics would you know how to define behavior FREQ at DC ?
I guess you are asking for the case where you are using FREQ to define a resistor - to help with establishing the DC operating point. For this use case, the DC value of the resistor will be the x in R=x FREQ (...) ; I used 1 but you can use any other value there, its just that the FREQ table admittances need to be re-scaled to take into account the initial DC "x" value. If you need an infinite DC value, you can put the resistor in series with a capacitor that has a capacitance of 1 (1farad) - this way its an open circuit under DC conditions and more or less 0 ohm under your use case frequency.
@@FesZElectronics Thanks, I'll try.
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