Compatability with LTspice?

I’d appreciate some input from Qorvo regarding compatibility with LTspice schematic files.

I’m a long-time LTspice user/fan and have incorporated it into the curriculum of several courses. I’m just starting an evaluation to determine whether incorporating Qspice into future coursework makes sense. I quickly encountered a significant roadblock: the apparent lack of compatibility with LTspice schematic files.

I’ve amassed a substantial collection of files that would require import/conversion, and the prospect of manually recreating schematics in Qspice is probably a show-stopper. I found comments on this issue in another thread but didn’t see a clear solution or any input from Qorvo (unless I missed it). I searched the documentation using the “LTspice” and “Import” search terms but only saw a reference to model import, not schematic files.

If there is no compatibility, then I’d recommend stating it outright. Regardless, I’d be grateful for a response from the authoritative source - Qorvo.

Ltspice has original models that are not found in other Spice programs. Many models are encrypted. No outsider has the right to use them. Qspice has original models. Therefore, you should not expect compatibility between the schemes. Since the models are different and they are not in Qspice, transferring the circuit from one program to another is not possible. But enthusiasts make character translators, and if there are spice models for these characters not in the LTspice syntax, then you can make a Qspice element.
My advice: don’t leave LTspice. But I advise you to use Qspice because of the new features. For example, the ability to build models using Verilog and C++.
I expressed my opinion.


Ordinarily, I wouldn’t expect compatibility between products from two manufacturers. I only did so in this case after seeing that the major contributor, Mike Englehardt, was common to both companies. In fact, I only considered using Qspice after seeing a video of M.E.'s Qspice announcement at a trade show. I naively assumed the new version would be compatible without considering IP/Licensing issues.

Thanks for the prompt response and the advice; much appreciated.

I fully agree with @bordodynov , this is only additional information for reference.

Device Compatibility
The major device not compatible from LTspice is A-device, which unfortunately is commonly used in LT and AD devices subckt. Two reasons that A-device is not implemented in Qspice according to Mike Engelhardt

Depends on how A-device is used in LTspice model, it may or may not be translate into Qspice. But no matter how it done, there is no way for full compatibility from A-device to Ã-device.

If A-device is not involved, you should generally able to work between simulators with netlist. Schematic file is always unique to the simulators GUI, but netlist is universal (sometime you may still need few modification). This is a common method that people use it to compare Qspice with different spice simulators.


I remember reading somewhere that the primary reason why LTspice, Simplis-ADI, Tina-TI exist are for those big suppliers to distribute their own encrypted circuit model thus the user can simulate and study their IC without leaking too much info to the user/competitors.

I think, this reason aloneshould be sufficient to indicate that cross compatibility wont be the developers priority anytime soon.

I also have a large number of LTspice schematics, and I fully agree automatic conversion to Qspice would be a big time saver.
It would not be fully automatic if incompatible devices are used, and they would need extra work, but that is unavoidable in any case.

It would be excellent if there was a LTSpice-to-QSpice converter. But I"m pretty sure that Mike is prohibited contractually from doing it. (Surely this would violate some non-compete terms.)

So I suspect that, if we want it, we’ll need to build it ourselves. I spent a bit of time reverse-engineering the *.qsch format for my QCodeGen project and the QSpice side seems easy enough. If anyone wants to make it a team effort, count me in.