0173-2023-11-18.md

18 Nov 2023

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Starting sky130A analog ASIC design: Setting up xschem

Base xschem installation

Guide: https://xschem.sourceforge.io/stefan/xschem_man/install_xschem.html

1. Starting with MPW8 VM. Xschem not already installed.
2. Install prerequisites:

   sudo apt install \
       libx11-6 libx11-dev libxrender1 libxrender-dev libxcb1 libx11-xcb-dev \
       libcairo2 libcairo2-dev tcl8.6 tcl8.6-dev tk8.6 tk8.6-dev flex bison \
       libxpm4 libxpm-dev libjpeg-dev tcl-tclreadline vim-gtk3 xterm

3. cd ~/asic_tools
   git clone https://github.com/StefanSchippers/xschem.git xschem-src
   cd xschem-src; ./configure

   Successfully ends with Configuration complete, ready to compile.
4. Build and install:

   make
   sudo make install

   We should now have:

   $ which xschem
   /usr/local/bin/xschem
   

Example sky130 project and config

Ref: https://youtu.be/KgBLByOkJxA?t=312

1. ln -s $PDK_ROOT ~/PDK
   cd ~/anton
   mkdir sky130_example
   cd sky130_example
   cp ~/PDK/sky130A/libs.tech/xschem/xschemrc .

   NOTE: This xschemrc uses $PDK_ROOT and $PDK but that's fine.
2. Run xschem, and...

Tips

• When xschem is running, type puts $XSCHEM_LIBRARY_PATH in the xschem tcl prompt to know the library search path.

  Type puts $XSCHEM_SHAREDIR to see the installation path.

• If you need to override system settings, create a ~/.xschem/xschemrc. The easiest way is to copy the system installed version from ${prefix}/share/xschem/xschemrc and then make the necessary changes

  mkdir ~/.xschem
  cp <install root>/share/xschem/xschemrc ~/.xschem/xschemrc

• Re sky130A PDK xschemrc:

  #### values may be overridden by user's ~/.xschem/xschemrc configuration file
  #### or by project-local ./xschemrc

Next steps

• WATCHED: Stefan's Jan 2023 video "Analog simulation with xschem and the skywater 130nm Process Development Kit (PDK)"
• WATCHED: Efabless Webinar - Analog schematic capture & simulation with Stefan Schippers -- this might include the design from the video above?
• Efabless Analog layout using Magic and Klayout with Tim Edwards and Thomas Parry -- builds on the design above?
• Efabless Analog layout of an op-amp using the Magic VLSI tool -- might be the longer recording of the same 'Analog layout' video above?
• Maybe: Efabless Magic Tutorial 03 Creating a Cell Using Parametrized Devices -- NOTE: This might be an out-of-order continuation of:
  • Magic Tutorial #1 - Highlight of Magic Features
  • Magic Tutorial #2 - Using cells, copy, move and wiring
• Efabless GF180MCU Tutorial - Single Video
• Go back over Z2A Part 1