I recently rushed to make a tapeout using Caravan (the analog Caravel). Here a few learnings that caused me quite of bit of lost time, so maybe helpful for others: * Magic changes cells when reading in a GDS. When this is not wanted (e.g., when using an existing IP block in GDS form as part of a larger design), then before reading the GDS with

gds read file.gds

in Magic do

gds readonly true

. * This sets the property

GDS_FILE

in Magic, that it uses as reference when writing the GDS from the MAG file later. * When a cell needs to be changed, this property has to be removed by doing a

property GDS_FILE ""

on this cell. * The SPICE netlist of the analog design normally resides in the

xschem

folder. However, in order to pass the consistency check of the MPW-precheck of efabless, the netlist has also to be placed into the folder

netgen

. * Run a local mpw-precheck early in order to detect issues. The DRC ruleset from KLayout can differ to whatever one is using locally, so expect new DRC errors to pop up. * This repo <https://github.com/iic-jku/sky130_adc_202311> passes all the mpw-prechecks and the TO procedure on the efabless site, so can be used as a reference and template.

Many thanks to @Harald Pretl for defining a good analog flow!

Thanks @Harald Pretl Cc @Alfonso Cortés @Mario Romero

@Patrick Fath is currently doing extensive simulations using

ngspice

and

xyce

. Patrick, any hints? @Jorge Marin Can you maybe describe your crashes a bit further?