flipflop_demo

Interactive flip flop simulation

Made for a video about flip flops: https://www.youtube.com/watch?v=5PRuPVIjEcs

For the Zero to ASIC course

To play with bundled data set from SKY130 df transmission gate flip flop

git clone https://github.com/mattvenn/flipflop_demo
cd flipflop_demo/spice
tar xf csv.tar.bz2
./wave.py

You will probably need to install the requirements

pip3 install -r spice/requirements.txt

If you want to build the GDS of the design

After install of openlane/pdk etc, copy this directory to $OPENLANE_ROOT/designs. Then:

cd $OPENLANE_ROOT
make mount
./flow.tcl -design flipflop_demo

Create the dataset yourself

This will simulate moving a data pulse through the setup and hold times of a d type flop.

make setup
make sim

Takes about 8 mins on my laptop.

Schematic generated with schemdraw with thanks to Proppy.

Fun facts

The flip flop is one of the largest and most complex standard cells. Here’s the GDS layout:

• 26 fets, 13 CMOS pairs
• 7 inverters
• 2 tristate inverters
• 2 transmission gates