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Re: About impedance
Tony Casey
--- In LTspice@..., Philip Bellingham <rmhc78a@...> wrote:
Hello Philip, Thanks for the info. I'm aware of the Smith chart add-on, which is why I said native. It's clever as you said, but not slick enough for serious design work; even the author concedes it's crude. I'm also aware that adding the .net directive enables an .ac analysis to generate S-parameters; and indeed, I make a lot of use of this feature. But you cannot use S-parameters as input data. This was my point, although I admit I didn't make that very clear. There are also various utilities that claim to generate SPICE subcircuits from S-parameter files, but this is something of a holy grail, which is why the only commercial product that really claims to have cracked this with multiport demonstrable accuracy over decades of frequency range costs thousands of dollars. Regards, Tony |
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Re: Diode Model Request for 1N5811 and 1N6628
Oh, I just noticed that you wrote in the subject line 1N6628 and in the text 1N6618. Which one is your favourite? If you need 1N6628, I will try to create a model, too.
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Gerhard --- In LTspice@..., Dan Chamberlin <dachamberlin16@...> wrote:
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Re: Diode Model Request for 1N5811 and 1N6628
Hello Dan,
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these are approximate models for the requested diodes, newly created from the datasheets' curves/values: .model 1N5811 D(Is=850n N=1.938 Rs=4.235m Ikf=2.584 Xti=3 Eg=1.11 Cjo=146p + Isr=378E-30 Bv=160 Ibv=100u Tt=43.3n Iave=6 Vpk=160 mfg=Microsemi type=Silicon) .model 1N6618 D(Is=620.6u N=5.430 Rs=15.4m Ikf=.662 Xti=3 Eg=1.11 Cjo=192p + M=.414 Vj=.184 Isr=372E-30 Bv=800 Ibv=1u Tt=173n Iave=3 Vpk=800 mfg=VMI type=Silicon) Best regards, Gerhard Kaufmann --- In LTspice@..., "dachamberlin16" <dachamberlin16@...> wrote:
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Re: AD8336 failure
--- In LTspice@..., "stm6823@..." <stevemorris@...> wrote:
Hello STM, You can see my attributes in the text file above. It's different from what you had in your your symbol. Normally you don't look with a text editor. You should open my symbol with LTspice and then "Edit->Edit Attributes...". Modelfile: ad8336.cir Value: AD8336 Value2: AD8336 Best regards, Helmut
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Re: Diode Model Request for 1N5811 and 1N6628
Tony Casey
--- In LTspice@..., Dan Chamberlin <dachamberlin16@...> wrote:
Hello Dan, If you can't find models for your diodes, it's not the end of the world, but it will involve more work. (But think of the satisfaction.) Firstly, for a tutorial, start here: Then, you can download Hendrik's Diode Modeler from here: Read the instructions, if necessary, then brew you own models. Create an LTspice test jig and check the curves against those in the datasheet, and you're good to go. Now you're equipped to tackle almost any diode job regardless of whether there already exists a SPICE model for the device. Note: many manufacturers' models are garbage anyway, so it's always good practice to check them in a test jig before using on anything important. There is also a VMOS modeler from the same author in the Files section. Regards, Tony |
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Re: .savebias command commented out
g.moberg
Hello Again,
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Just to finish this topic out, today I generated the "Skip" file successfully. Since this is an SMPS circuit whose inductor currents are not zero, I edited the "Skip" file to change its .nodeset command to a .ic command, and set the initial conditions of the 2 inductors to their approximate values at the time the .savebias command executed. This changes the inductor characteristics for initial convergence from short circuits to ideal current sources with the specified initial conditions. This must be done to prevent the circuit from converging to a highly erroneous state with 0V across the inductors. The simulation picked up very close to where I expected it to, and settled quickly so I can do the load transient analysis without waiting minutes to get to a settled condition. Thanks again for those who looked at this. Greg Moberg --- In LTspice@..., "g.moberg" <gregory.moberg@...> wrote:
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Re: AD8336 failure
Tony,
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You are right about the path - I messed up, sorry. I will follow the check box suggestion from now on. Thanks again, STM --- In LTspice@..., "Tony Casey" <tony@...> wrote:
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Re: AD8336 failure
I opened the AD8336.asy you had in the zip file with FILE OPEN in LTspice but I don't find any attributes.
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When I open it in notepad the only attributes are pin references. Version 4 SymbolType BLOCK RECTANGLE Normal -80 -104 80 104 WINDOW 0 0 -104 Bottom 2 WINDOW 3 0 104 Top 2 SYMATTR Value AD8336 SYMATTR Prefix X SYMATTR SpiceModel ad8336.cir SYMATTR Value2 AD8336 PIN -80 -64 LEFT 8 PINATTR PinName GNEG PINATTR SpiceOrder 1 PIN -80 -32 LEFT 8 etc. How do I open the others to see what you set? Thanks, STM --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
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Re: AD8336 failure
--- In LTspice@..., "stm6823@..." <stevemorris@...> wrote:
Hello STM, I made a specific symbol which isn't editable. All symbol of the LTC-opamps are made this way. Please open the symbol(.asy) with LTspice to see which attributes I have set. Best regards, Helmut |
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Re: About impedance
Tony,
While LTspice may not be the ideal tool for RF design, it can still be quite useful. You are correct that it does not have native support for producing a Smith chart. However, some clever contributor to this group has provided a means to plot the graticule of a Smth chart and impedance curves with frequency markers (Files > Examples > Apps > SmithLTspice.zip). ? With respect to LTspice handling s-parameters, it certainly can. The .NET command computes network parameters in an AC sweep. The HELP files says in part, ? "This statement is used with a small signal(.AC) analysis to compute the input and output admittance, impedance, Y-parameters, Z-parameters, H-parameters, and S-parameters of a 2-port network. It can also be used to compute the input admittance and impedance of a 1-port network. This must be used with a .AC statement, which determines the frequency sweep of the network analysis." ? There is an entire section in the tutorial section of this groups files devoted to s-parameters in LTspice (Files> Tut> S-Parameter). ? All the best, ? ?? - Philip ________________________________ From: Tony Casey <tony@...> To: LTspice@... Sent: Thu, September 15, 2011 8:55:18 AM Subject: [LTspice] Re: About impedance ? --- In LTspice@..., "keantoken" <keantoken@...> wrote: Hello Keantoken, If you're doing RF design, on oscillators, for example, it is essential to be able to see both real and imaginary parts clearly and separately without having to do mental arithmetic for each frequency displayed. The Cartesian presentation shows this much better for most people, although a few will claim they can glean everything they need from a polar plot. But then some people are able to write a complete GUI in one line of C. For doing serious RF design, LTspice is not the ideal tool, since it does not have native Smith chart and cannot handle S-parameters, but it is at least possible. Regards, Tony [Non-text portions of this message have been removed] |
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Re: Hey i am working on a Class D amp project, need help about LT Spice
Tony Casey
--- In LTspice@..., "cukkacan" <mustafa_cukka@...> wrote:
Hello, I don't know which web you checked, but there are thousands of links relating to class D amplifiers, many of them on the semiconductor manufacturers' websites, check there first. In general, you will only find people here keen to help once you have demonstrated a willingness to try. Start but drawing a schematic, try to make it work, then ask for help when it doesn't. So far, there's no evidence that you have done anything at all. Regards, Tony |
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Re: AD8336 failure
Helmut,
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Thank you very much for your time and help. So much for me to learn. I integrated all your schematic changes into mine and it works great. I put the changes in one at a time to observe the effect. Lots of subtle stuff like the series resistance in the supplies messing things up that I don't get. I am curious about your reference to correcting the symbol because I am still using mine and it works OK. I had LTspice make it from the netlist editor. I tried to open yours to see what you changed but it is not editable. What did you change? Thanks again, STM --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
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Re: About impedance
Tony Casey
--- In LTspice@..., "keantoken" <keantoken@...> wrote:
Hello Keantoken, If you're doing RF design, on oscillators, for example, it is essential to be able to see both real and imaginary parts clearly and separately without having to do mental arithmetic for each frequency displayed. The Cartesian presentation shows this much better for most people, although a few will claim they can glean everything they need from a polar plot. But then some people are able to write a complete GUI in one line of C. For doing serious RF design, LTspice is not the ideal tool, since it does not have native Smith chart and cannot handle S-parameters, but it is at least possible. Regards, Tony |
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Re: AD8336 failure
Tony Casey
--- In LTspice@..., "stm6823@..." <stevemorris@...> wrote:
Hello STM, It's possible I looked before the files were actually there, but when I found them they were in Files>Temp>AD8336, not Files>AD8336. It's also helpful when uploading files, to check the box about making an announcement to the group with a comment, not least because that message will have the correct hyperlink to the uploaded file because it's autogenerated and not prone to user error. I'm glad Helmut sorted you out, though, as he usually does when others fail. Regards, Tony |
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Re: Simple model for diffin-diffout amp
ehydra
Indeed, and that is the reason why I just use the datasheet and the universalopamp symbol to get rid of the problems. Most times the universalopamp makes a better job.
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- Henry -- ehydra.dyndns.info RobertTalty schrieb: The Microchip opamp spic models are very complex and attempt to model all types of errors and their Temp variations, but in the end these models cause convergence problems, so what is the point of a complex model that causes beginners convergence problems. Convergence can be hard for experienced spice users to solve, so it is the last thing that beginners need. |
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Re: AD8336 failure
Tony,
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Thanks for answering. I thought FILES\AD8336 in my help request would indicate where all the files were. Is there another way I should have done it? STM --- In LTspice@..., "Tony Casey" <tony@...> wrote:
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Re: adding noise to the model of a sensor
--- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
Thank you, noisegen.asc + noisegen.asy is what I needed! Ruggero |
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