open-source-silicon.dev

Hello all, 
Hope everyone here is well 
I have a basic doubt from xschem can anyone suggest me that how can I give the sine input  voltage source in xschem circuit ?

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Here it is. Use the standard `vsource.sym`. In case of expressions with spaces use quotes:
`value="sin(....)"`

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But in mine sine wave is not coming it's showing waveform like this as I am trying to running the opamp as a comparator but it's not showing sine waveform . 
It's showing waveform only straight line

<@U01819B63HP> sir can you please suggest me the problem and solution that's why the sine waveform is not coming ?

Isn't the third parameter the frequency? You seem to have 0.1mHz, which would have one cycle every 100 seconds

It's still not working , it's still showing the same waveform that is that straight line . How to solve it now ?

<https://ngspice.sourceforge.io/docs/ngspice-html-manual/manual.xhtml#magicparlabel-74125|https://ngspice.sourceforge.io/docs/ngspice-html-manual/manual.xhtml#magicparlabel-74125>

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Tried this one also, as given in the ngspice manual but it's still showing that same waveform of straight line

Use only 4 parameters in the sin function:
Offset, Amplitude, Frequency, Delay:

`value="sin(0.9 0.9 100MEG 5n)"`

In your last example the last parameter is a damping factor, which damps the voltage source to its offset value (0 in your case). A value of 1e10 damps the sine waveform to 0 within ~0.5ns

also, if you want to see a 100MHz sine wave it would be better to use ".tran 3n 10n" instead

but as Stefan said, if you don't damp it so quickly (it is a pulse lasting only a fraction of a cycle with your parameters) then even simulating a millisecond you would see something

<@U02AZSA6VFU>, <@U018NEYK53K> comment is also very important. If you want to see a 100MHz waveform you can not simulate 1ms with 3ms timestep (!) as suggested use `.tran 3n 10n`
EDIT: use `.tran 3n 100n` so you see 10 cycles of your 100MHz waveform.

Thank you sir I have tried this and sine wave have come but now can you please tell me that sir , why my output is coming in negative ?

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IMG_20230309_000015.jpg,IMG_20230309_000046.jpg

Please read the ngspice user manual. In the `sin(...)` function the first parameter is the offset. If you want a positive sine waveform you must add an offset value to make it all positive, like in:
`sin(1.5 1.5 50MEG 0.5n)`

Your `vss` node is also set to -1.8V This is certainly wrong.set the v3 voltage source to 0V