Welcome!

Howdy, just started the channel to talk about some issues that we were encountering in #piel with `simattr`'s, specifically

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- how does it work, why does it break in Xyce, etc.

Improved docs on

simattr

would be great, I think there's also stuff that is "unsupported" in vlsirtools that is supported and how you use something like "AC" is non-obvious.

(Seeing as the DcVoltageSource is the AC)

Hi, how was DC Analysis with

h.sim.LinearSweep

intended to function?

@h.sim.sim
class DeviceSim:

    @h.module
    class Tb:

        # Set up our ports
        VSS = h.Port()
        VDD = h.Signal()
        
        # Define our voltages
        x = h.Param(dtype=h.Prefixed,desc='my voltage')
        vdd = h.DcVoltageSource(dc=x)(p=VDD, n=VSS)
        # Instantiate our device
        DUT = device(d=VDD, g=vdd.p, s=VSS, b=VSS)

    dc = h.sim.Dc(var=x,sweep=h.sim.LinearSweep(start=0, stop=0.9, step=0.1))
    inc = s.install.include(h.pdk.Corner.TYP)

return DeviceSim

I think the implementation is actually missing in vlsirtools...

Ngspice appears to need the voltage source to be available in the top level in order to identify the voltage source with

.dc

I guess any kind of patch would have to expose a magic DC port on the testbench and voltage source which can be controlled by the

.dc

command.

Is this a bad idea, what do people think?

So, we have the answer - we have to let

.dc {param}

sweep over a linear range with 3 numbers, where

{param}

has to be

v.xtop.vvdd

(for your voltage source, etc.). Ngspice actually overloads

.dc

so it can be used to linearly sweep temperature

temp

, any current source, voltage source or resistor... sooo... what can we do? 1. Tell users how to hack the automated netlists to get the components that they actually want to manipulate 2. Expand VLSIR, create a good system of Enums to handle all the cases that ngspice calls

.dc

sweep analysis 3. Let users think they're controlling a

sweep

analysis when behind the scenes they're manipulating

.dc

commands

4. Introduce some sleight of hand - in Hdl21, where user puts in component name, provides a "type" Enum - resolve that into its awkward ngspice before it gets serialized and shuttled over to vlsirtools.