CMOS Folded-Cascode OpAmp Generator

Disclaimer

This is experimental.
This tool does not always generate working opamp parameters.
According to my test results, users still need quite much knowledge in analog IC design to make the generated parameters work well.
The value of this tool may be saving hand calculation time.

Usage

Install Node.js and git.
Open a terminal, enter the following commands (the same on Windows, Linux, macOS).

Clone the repository
```
git clone https://github.com/dragonman225/opamp-generator.git
```
Go into the directory
```
cd opamp-generator
```
Install Javascript libraries
```
npm install
```
Edit src/config.yml. Change the process dependent parameters and performance specifications.
Start the interactive generator
```
npm run start
```

Check below for instance names of the MOSFETs.

Advanced Stuff

Using lambda lookup table

To consider channel-length modulation and get optimized MOSFET sizes, a lambda lookup table is needed. However, since the relationship of lambda and gate length is process-dependent, I do not provide my lookup table here. You need to do a simulation using your process model and save the lambda v.s. gate length curve as a compatiple CSV file described below, then edit the config to import.

Make your CSV file look like this. It can contain arbitrary rows of data.
```
 length,lambda_n,lambda_p
 1.8E-07,0.6,0.4
 1.9E-07,0.58,0.36
 2E-07,0.55,0.33
```
- length is gate length in meters. lambda_n is lambda of NMOS. lambda_p is lambda of PMOS.
- Hints :
  - lambda = 1 / (Id * ro - Vds).
  - Do simulation with given Id, Vds, and measure ro to get lambda. You can sweep through a range of gate length, and plot the results.
  - To maintain Id at different gate length, W/L ratio need to be constant, so width should also change with gate length.
  - Export the plotted NMOS and PMOS curves as CSV, and use Microsoft Excel or LibreOffice Calc to combine them, also change the column names.
Open src/config.yml, edit the lambda_table property. Change its value to your path. Absolute path is recommended.
```
 lambda_table: your_csv_lookup_table.csv
```

Concepts of Design Procedure

Please see presentation file : https://slides.com/aic999/deck