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Re: Monostable VCO Schmitt problem
--- In LTspice@..., "zeeglen" <glen@...> wrote:
Can anyone explain why the difference between INV and SCHMITT?Try reading the Help file next time before spamming the group with your needlessly ignorant drivel. Quoting Help: ________________________________________________________ The gates default to 0V/1V logic with a logic threshold of .5V, no propagation delay, and a 1Ohm output impedance. Output characteristics are set with these instance parameters: Name Default Description ------------------------------ Vhigh |. 1 .| Logic high level Vlow .|. 0 .| Logic low level Trise |. 0 .| Rise time Tfall |Trise| Fall time Tau . |. 0 .| Output RC time constant Cout .|. 0 .| Output capacitance Rout .|. 1 .| Output impedance Rhigh |Rout | Logic high level impedance Rlow .|Rout | Logic low level impedance Note that not all parameters can be specified on the same instance at the same time, e.g., the output characteristics are either a slewing rise time or an RC time constant, not both. The propagation delay defaults to zero and is set with instance parameter Td. Input hold time is equal to the propagation delay. The input logic threshold defaults to .5*(Vhigh+Vlow) but can be set with the instance parameter Ref. The hold time is equal to the propagation delay. The Schmitt trigger devices have similar output characteristics as the gates. Their trip points are specified with instance parameters Vt and Vh. The low trip point is Vt-Vh and the high trip point is Vt+Vh. The gates and Schmitt trigger devices supply no timestep information to the simulation engine by default. That is, they don't look when they are about to change state and make sure there's a timestep close to either side of the state change. The instance parameter tripdt can be set to stipulate a maximum timestep size the simulator takes across state changes. |
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Re: Averaging a waveform
--- In LTspice@..., "jtanalog" <ltlist@...> wrote:
Hello Jim. Unfortunately it's not possible to directly define a formula with integration in the waveform viewer. One has to make a Bv-source in the schematic or netlist. .param d=100u .func avgx(x,d) {(idt(x)-delay(idt(x),d))/d} BV1 avgout 0 V=avgx(V(out),d) BV2 avg37 0 V=avgx(V(37),d) By the way you don't need a Bv-symbol. You could directly add these SPICE-lines from above to your schematic. You will need one B-device SPICE-line for every item you want to average. I tried an example and found it's necessary to define a small max time step in .TRAN and to switch off data compression for best results. .options plotwinsize=0 ; data compression off The text after ';' is only comment. Best regards, Helmut |
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Monostable VCO Schmitt problem
Hi all. I've just uploaded a file "Monostable VCO Schmitt problem.asc". The simulation works when a INV is used, but has problems when a SCHMITT inverter is used instead. Both use default values, and as far as I can tell they are identical other than the SCHMITT is about 4 usec more delay. The SCHMITT has no visible hysteresis when driven from a sine source.
V2 on the far left is the VCO control voltage. Up top there is a choice between INV A1 and SCHMITT A2. As long as INV A1 is in the circuit it oscillates with V2 as low as 0 volt. But if A1 is disconnected and SCHMITT A2 connected in its place the circuit does not oscillate when V2 is below 1 volt. The falling ramp from opamp U2 appears to get too small to cross an assumed lower trip point, yet there doesn't seem to be any difference between trip points; I have not changed Vt and Vh from the SCHMITT default values (not sure how). I am trying to replicate the Schmitt action of the trigger input of a 74HC221 monostable with the LTC6993-1 and the INV along with Q1. R10 and R11 are there to divide the opamp U2 output by 5 to switch at the A1 A2 threshold of 0.5 volt when U2 is 2.5 volt. Can anyone explain why the difference between INV and SCHMITT? Maybe I do need to set a value of 0 for Vh. Also tried SCHMTINV (A3), it has the same problem Thanks in advance. |
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Re: Averaging a waveform
--- In LTspice@..., "jtanalog" <ltlist@...> wrote:
Jim, I'm surprised you haven't looked at the LTspice help file. This is in the help under Waveform Viewer>Waveform Arithmetic. Rick |
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Re: How do I import the LMH6629 spice file into LTSpice IV?
Hello Jesper,
However, to be honest I still don't understand/know how theMy examples are for a universal symbol and a specific symbol. Please open the symbol files(.asy) with the symbol editor of LTspice and view the obvious differences in the attributes of both symbols. Edit -> Attributes -> Edit Attributes The netlist order in the pins start from 1 and ends with the number of pins of the subcircuit definition. The netlist order will be from 1 to 5 for a .subckt with 5 pins. Best regards, Helmut |
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Re: Multistage inverter-AC analysis
mario.chillemi wrote:
I update my version of multistage inverter in Ac analysis. Can you tell me ifMost often, people set the AC source amplitude to 1V. With your differential source, I'd use 0.5V for each of the two sources, to get 1V differential input voltage. The reason is that it makes it easier to see the voltage gain. Gain = Vout/Vin, and when Vin=1, Gain = Vout. So looking at the plot of Vout, it IS the voltage gain too. AC analysis is a "small-signal" linear (linearized) analysis, which means signal amplitudes don't actually matter. You could drive it with an AC amplitude of 100V and the analysis would be the same as if you had used 1uV. I suppose you might want to play with the DC offset voltage a bit (the DC voltage of V2), to see what effect it has on AC gain. Regards, Andy |
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Re: LTSpice & Eagle
I went looking on the eagle forums for answers on this too only to find that it looks like the eagle forums are no longer there.
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what link are you using to get to the eagle forums now ? even if unanswered ? thanks, boB --- In LTspice@..., "Gandolf" <gandolf_t_grey@...> wrote:
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Re: How do I import the LMH6629 spice file into LTSpice IV?
Hi again Helmut,
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& thanks for uploading the new files :-) Incidentally, you've actually helped me with a challenge I've had on how to make a tiny circuitry to measure HF noise in DAC/ADC supply rails: With a few modifications it looks as if the circuitry you've drawn up can be used for this ... Thank you! However, to be honest I still don't understand/know how the "complete" import of a component with a different pin layout and/or a new symbol is done. Might you be able to point me to a description of this - maybe here in this forum - that describes this for a sort of newbie, i.e. in an intuitive way and maybe step by step? I've been using LTSpice for some years now and know how to perform some setups and analyses but sometimes still need to take things step by step. Also, I am looking for an LTspice/spice model of one of those lamps that are used in oscillator designs to adjust the AGC of the feedback loop. I've searched the files here and found some but am unsure which one to use. I'm considering building an oscillator similar to the one shown in the LT1007 spec sheet (ultrapure sinewave oscillator): but at a higher frequency (1 - 10 MHz if possible). Would you off the bat know which of the lamp files to use? Once again, thanks for your previous help, Helmut. And BTW if the simulations LMH6629 simulations are realistic it looks as if it's a quite well-designed component - not easy to make unstable. Impressive actually ... Greetings, Jesper --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
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Re: Spice Model
Basier philippe <basier.philippe@...> wrote:
Should I have to understand you have still problems with opening all_files.htm ?Yes. The problem has not gone away. I am seeing similar problems with many other Yahoo!groups too. Ordinary text files and HTML files that used to open when clicked on, now can only be downloaded. Regards, Andy |
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LTSpice & Eagle
Some background, not intended to be criticism, then the question.
Cadsoftusa's Eagle 6.4 introduced an interface to link schematics with LTSpice IV for simulation. Unfortunately, the link does not seem to be fully functional. There is no documentation from Cadsoftusa about this link that I have been able to find. Cadsoftusa's website points to Newark (Element 14) for technical support. Newark (Element 14) has a number of Eagle Webcasts but these have provided limited help. Also, their forum questions go un-answered. In fairness, Newark (Element 14) is in the business of selling, not providing implementation details of a product; they do provide LTSPice IV models and Eagle symbols and placement data for many components. I have been able to create a link Eagle 6.4 to LTSpice IV but have not been able to transfer a schematic for simulation. Separately, I have been able to download spice models and symbols and integrate them into LTSpice IV for simulation. Separately, I have been able to download and integrate schematic symbols and placement data into Eagle 6.4. Getting the two products to work an play together seem to be problematic. The Question: Has anyone in the forum had any experience with using the Eagle 6.4 link to LTSpice IV and can provide any guidance or point to potential information. Using a link like this seems to be a good idea and I would like to take advantage of it. I'll keep trying different things as time permits. |
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Re: How through external program calls LTspice
Does not the LTspice help file (under "Modes of Operation" -> "Command Line Switches") have sufficient information?
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Donald. -- *Plain Text* email -- it's an accessibility issue () no proprietary attachments; no html mail /\ ascii ribbon campaign - <www.asciiribbon.org> ----- Original Message -----
From: "He" <he.yang@...>[snip] |
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Re: diode model with formulas and nodes
Thank you very much for your guides.
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Actually I tried the formula for the diode and I did not get an answer. Therefore, I upload my complete circuit. in this circuit which is a solar cell, when I put two cell in series, I have a distortion but when I put the in parallel, I have the right answer which I think is because of the diode design. could you have a look on it ? you can find the file in FILES>Temp>cell_beh1.cir Kind regards Hamed --- In LTspice@..., "hamed" <l0st_l0rd@...> wrote:
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Re: How through external program calls LTspice
Hallo Tim,
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Thank u very much for the message, i know that i can use python to write the script. but i don't know how should i programm then i can use the python to call LTspice. can you show me an example? or just how should i script？ i cant find it in the internet. thanks again! regards Yang --- In LTspice@..., Tim Jameson <tim@...> wrote:
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Re: Slow simulation on new version of LTspice
Okay. Thanks Helmut for the modifications.
Now this simulates quite fast. ? Regards, Vaseem ________________________________ From: Helmut <helmutsennewald@...> To: LTspice@... Sent: Friday, July 5, 2013 1:21 AM Subject: [LTspice] Re: Slow simulation on new version of LTspice ? --- In mailto:LTspice%40yahoogroups.com, mohd vaseem <vaseem_vlsi@...> wrote: Hello Vaseem, I haven't checked with an old version. I simply looked forward and changed your circuit. The two AND-gates improved the sim- speed by a factor of 1.5. The comparator improved it another factor of 4. Over all it's now 6 times faster. I hope this helps. Right-mouse-click on my digital devices to see their attributes. Files > Temp > dc_dc_pfm_and.asc Best regards, Helmut [Non-text portions of this message have been removed] |
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My collection of models and examples for LTspice.
Hello All.
My collection of models and examples for LTspice contains a large number of models. It includes a collection of EXTRA. This collection EXTRA I expanded with new models and changed the characters of digital items. Now you do not need a reference to the library. The collection contains a lot of operational amplifiers described in bulk (one character and a lot of models). Also, it has a model of the photodiodes, avalanche photodiodes, avalanche transistors, lasers, and many other items. In folder example a lot of good examples. File is LTspiceIV.zip (34Meg). Link ---> Bordodynov. |
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Re: Spice Model
Hello Andy,
You wrote : Download the following file from the group's website:Should I have to understand you have still problems with opening all_files.htm ? Regards, Ph. B. --- In LTspice@..., Andrew Ingraham <Andrew.Ingraham@...> wrote:
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Re: Multistage inverter
mario.chillemi wrote:
thank you Mr Bordodynov,the circuit is perfect.Can I useYes. You will need to assign AC values to one or both of the sources, V3 or V2. Right-click on the voltage source, click the "Advanced" button, find the "Small signal AC analysis" area, and fill in a non-zero value for the "AC Amplitude". (Note that AC analysis and Transient analysis are totally separate from one another, so don't bother with the PULSE, SINE, etc. area unless you intend to do a Transient analysis instead.) You could give AC values to both V3 and V2, in which case you might want one of them to have AC Phase = 180 degrees (balanced input). Note that the capacitance values in Bordodynov's version are rather large. The MOSFETs default to 20 by 20 microns, which is old technology. Regards, Andy |
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