Transistor I-V Measurement Starter

This project gives you a clean baseline for automating transistor I-V measurements using instruments connected through USB-to-RS232 adapters.

What it does

• Talks to two serial instruments:
  • gate_source: sets gate voltage
  • drain_source: sets drain voltage and reads drain current
• Sweeps VDS for each VGS
• Saves all measurement points to CSV
• Can run a full table of routines from a CSV file

Quick Start (Windows)

1. Create a virtual environment:

py -3 -m venv .venv
# Transistor I-V Measurement Starter

This project provides a Python interface for transistor I-V measurements using instruments connected through USB-to-RS232 adapters.

The main entry point for a single measurement routine is `run_routine.py`.

## What the Python code does

- Reads the instrument definitions from `instrument_list.yaml`
- Loads one routine from a routine CSV file
- Programs the configured gate, drain, and optional bulk/auxiliary sources
- Sweeps the selected routine parameters and records `Ids`
- Writes all measured points to CSV
- Shows a live plot while running, unless disabled

## Quick Start (Windows)

1. Create a virtual environment:

```powershell
py -3 -m venv .venv
.\.venv\Scripts\Activate.ps1

2. Install dependencies:

pip install -r requirements.txt
pip install -e .

3. Edit instrument_list.yaml so the ports and SCPI commands match your hardware.

4. Run a single routine with run_routine.py.

Running run_routine.py

The script accepts a routine index and several optional settings. By default it uses a simpler two-wire drain measurement. Pass --four-wire to enable remote sense.

Basic usage

python run_routine.py --routine-index 0

Copy/paste example

python run_routine.py `
  --config instrument_list.yaml `
  --routines-csv "Routines/Cryo PDK DC measurement routines - nMOS 28nm.csv" `
  --output-csv data/first_routine_measurements.csv `
  --routine-index 0 `
  --ids-settle-s 1.0

Arguments

• --config
  • Path to the instrument list YAML file.
  • Default: instrument_list.yaml
• --routines-csv
  • Path to the routine definition CSV.
  • Default: Routines/Cryo PDK DC measurement routines - nMOS 28nm.csv
• --output-csv
  • Path where measured points are written.
  • Default: data/first_routine_measurements.csv
• --routine-index
  • Zero-based index of the routine to run from the routine CSV.
  • Default: 0
• --no-live-plot
  • Disables the live matplotlib plot.
• --no-confirm-initial
  • Skips the manual confirmation pause after the initial voltages are applied.
• --four-wire
  • Enables Keithley remote sense for the drain source and caps the source range at 2 V.
• --ids-settle-s
  • Delay in seconds before each Ids measurement.
  • Default: 1.0

Inputs

1. Instrument list YAML

The instrument list is the hardware configuration file consumed by the Python code.

It defines:

• Each physical instrument and its serial port
• The SCPI command strings used to program each instrument
• Which logical measurement role each instrument plays

The current file is instrument_list.yaml.

Important fields:

• instruments
  • Contains one entry per physical instrument
• type
  • Identifies the instrument family, such as Keithley2400, E3631A, or 9132C
• port
  • The serial port, such as COM5, COM6, or COM7
• quantity or channel_map
  • Maps the instrument to logical roles like Vg, Vd, Vb, vgxp, and vgxn

Example:

instruments:
  keithley_2400:
    type: Keithley2400
    port: COM7
    quantity: Vd
  keithley_e3631a_a:
    type: E3631A
    port: COM5
    channel_map:
      P6V: Vb
      P25V: Vg
      N25V: None

2. Routine CSV file

The routine CSV tells the script which measurement to run and how to sweep it.

The current routine file is Routines/Cryo PDK DC measurement routines - nMOS 28nm.csv.

The script reads these columns:

• Measurement
• Parameter to sweep
• Sweep Start
• Sweep Stop
• Num Sweep Points
• Parameter to Step
• Step Start
• Step Stop
• Num Step Points
• Vg Init
• Vb Init
• Vd Init
• Vs Init
• vgxp Init
• vgxn Init

The --routine-index argument selects which row to run.

Arduino requirement

For now, the Arduino code must be loaded onto the board independently before running the Python scripts.

In other words:

1. Flash the Arduino separately using the code in Arduino/
2. Verify the board is running the expected firmware
3. Then run run_routine.py to operate the instruments

The Python code does not upload Arduino firmware for you.