If you are interested in exploring alternative circuit simulation systems, the Micro-Cap mixed-signal circuit simulation system is now available for free here: http://www.spectrum-soft.com/download/download.shtm.
The CD that you can download is targeted at Windows users, but I have installed it under WINE on my Ubuntu 18.04 Linux computer, and it appears to run perfectly.
It comes with really good documentation (user's guide and reference manual) and what appears to be a very comprehensive component library.
I've just started to explore the capabilities of this system, but so far I am very impressed.
The CD that you can download is targeted at Windows users, but I have installed it under WINE on my Ubuntu 18.04 Linux computer, and it appears to run perfectly.
It comes with really good documentation (user's guide and reference manual) and what appears to be a very comprehensive component library.
I've just started to explore the capabilities of this system, but so far I am very impressed.