@User how would you recommend the best way to characterise an on chip inductor? I know you mentioned before increasing the bias current till the oscillator starts. But what would be the best way of testing just the inductor itself? Or we should still use an oscillator as a piece of test equipment essentially?

I just want to make sure someone tapes out an inductor that we can measure and correlate with a model on this first run - I'm happy to do that if no else is already planning on it

Hi all. Back after another work related hiatus

Hello Trevor, how have you been?

Did you have a look at the caravel harness? Seems like project area is more like 2.8mm x 2.8mm.

I haven't had a chance to yet....checking it out tonight

no sure if I'm going to have time to get to it for the first run but this would be a great device to try and get on the initial shuttle if someone has bandwidth

Hello all, I am a uni student in the US and interested in developing VHF+ LNAs, PAs and some mixers with the sky130 pdk. I've been aware of the project for a while but haven't started looking into everything seriously until now. I am just beginning the process of installing available opensource tools and familiarizing myself with the pdk. I am very excited to start working and hope to be able to fabricate a chip early next year in later shuttle launches.

@User I was the instigator for this channel but there have been a few of us working on this front. What's your experience with RF and VLSI design? I'm working on a gilbert cell mixer and LNA and filter cells but I have no VLSI background so it's slow going getting transistors sized and modelled. I could certainly use some help.

If you scroll through the logs for this channel (they aren't too long) you'll see some other projects. Also check #analog-design as it has some relevant information as well

I found this talk by Enrico Di Lorenzo of https://www.fastfieldsolvers.com/ quite interesting: https://peertube.f-si.org/videos/watch/81951ef3-5914-4d21-99cf-b8019e698711

A heads up to anyone trying to use the RF PMOS devices, there's an issue with the pin ordering. It can easily be fixed by altering the sub-circuit but incredibly frustrating if you're not aware of the issue - I know from experience https://github.com/google/skywater-pdk/issues/212

That must have been hell to debug.

@User has come cross some important information regarding the RDL and future shuttle runs. They tagged the channel but I didn't receive a notification. Sharing in case people haven't seen it.

@User: You can try to persuade Tim Ansell otherwise. I was in favor of removing the four bump bonds from the middle of the die and using that space for inductor tests. However, keeping costs down seems to be the overriding factor here. Personally, I don't see it as a huge overhead because the masks for the bump bonds are the eqivalent of a 2um process or something like that and are much cheaper than the SkyWater masks. You can try to lobby Tim Ansell with all the great radio projects you could potentially do. Personally, I would prefer to set aside one of the reticle areas with an experimental inductor. Ultimately, even if we decided to do it in the future, I think there is just not enough time for this shuttle. From a thread in #sky130

@User If on subsequent tape-outs people will not have the automatic option of putting more inductors on the RDL, then I'm not going to push to do it this time to characterise/test them. For next time it would be interesting to quantify the mask cost though - individual users might think it worth paying. Anyway, if RDL inductors are not going to happen then it would be good to announce that in #radio so that people have time to adjust their designs accordingly. Provided there is a >=500um diameter region somewhere with no RDL or bumps above it, the Skywater layers are thick enough to make usable inductors, albeit probably a bit worse than the RDL. From a thread in #sky130

@here any recommendations for EM simulators

?

Does the PDK provide the eps of all layers?

@User The stackup diagram provides all the dielectric constants and the resistivity is available in the PDK docs. Alternatively have a look at this file It contains all the required data to reconstruct the geometric structure for meshing in a convenient place.

@User For EM simulation, the open source ones that are most accessible are openEMS, and FastHenry2 + FaserCap. Geometry description in FH can be a pain if the design is complicated. openEMS needs processing of the GDS files to extract the polygons. KLayout does a good job here. It has a CSG engine that is easy to work with. Here's a sample setup file that should get you started. https://github.com/diadatp/sky130_rf_tools/blob/main/openems/main.m Be prepared to wait a long time for simulations to run. Especially if you set the correct boundary conditions.

Hi @here Posted in #analog-design

We are happy to announce that we have created a script that installs all the tools necessary for starting with Skywaters 130 Posted in #analog-design

mabrains/sky130_ubuntu_setup Ubuntu scripts that are used for setting up your machine for Sky130 designs. mabrains/sky130_ubuntu_setup

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