cace 2.2.3

Circuit Automatic Characterization Engine

CACE

Circuit Automatic Characterization Engine

CACE is a set of python scripts that take an input file in the CACE 4.0 format and uses the information found there in combination with CACE-compatible testbenches and analysis scripts to characterize a circuit and to produce a datasheet showing the circuit performance.

Installation

You'll need the following:

• Python 3.8 or higher with PIP and Tkinter

CACE can be installed directly from PyPI:

$ python3 -m pip install --upgrade cace

Prerequisite design tools:

• xschem: https://github.com/stefanschippers/xschem
• ngspice: git://git.code.sf.net/p/ngspice/ngspice
• magic: https://github.com/RTimothyEdwards/magic

Some of the measurements require:

• octave: https://octave.org/

Usage

If installed as Python package, CACE can be started from the command line using:

$ cace

Or to start the GUI:

$ cace-gui

Information on how to use CACE can be found in the documentation at cace.readthedocs.io.

Development

Dependencies

[!IMPORTANT] You may need to set up a Python virtual environment.

To install the dependencies for CACE, run:

$ make dependencies

Python Package

To build the Python package, run:

$ make build

To install the package, run:

$ make install

To install the package in editable mode, run:

$ make editable

Documentation

To build the documentation, run:

$ make docs

To host the docs, run:

$ make host-docs

To automatically refresh the docs upon changes, run:

$ make auto-docs

[!NOTE] The latest documentation can be viewed online at cace.readthedocs.io.

Examples

The following repositories contain example circuit designs, each having a "cace/" subdirectory with a specification input file in the format described below, and a set of testbench schematics which are used by CACE to measure all specified electrical and physical parameters, generate results, and analyze them to determine circuit performance over corners.

[!NOTE] Example repositories, like CACE itself, are currently a work in progress.

All repositories are rooted at: https://github.com/RTimothyEdwards/.

Example circuit repositories:

• sky130_ef_ip__instramp Instrumentation amplifier
• sky130_ef_ip__rdac3v_8bit 8-bit resistor ladder DAC
• sky130_ef_ip__samplehold sample-and-hold circuit
• sky130_ef_ip__driveramp Rail-to-rail driver amplifier
• sky130_ef_ip__ccomp3v Rail-to-rail continuous comparator
• sky130_ef_ip__rc_osc_500k R-C oscillator, 500kHz nominal output
• sky130_ef_ip__xtal_osc_16M Crystal oscillator, 4 to 15MHz
• sky130_ef_ip__xtal_osc_32k Crystal oscillator, 32kHz

Each of these repositories contains a circuit designed with the SkyWater sky130 process open PDK, and contains schematics, layout, and CACE characterization.

[!NOTE] These repositories are a work in progress, and may not exist yet or may not have a characterization setup for CACE.