### Install SkyWater PDK and Libraries

Source: https://context7.com/google/skywater-pdk/llms.txt

Commands to clone the repository, download standard cell submodules, and generate timing files.

```bash
# Clone the SkyWater PDK repository
git clone https://github.com/google/skywater-pdk.git
cd skywater-pdk

# Download all standard cell libraries (large download ~7GB)
SUBMODULE_VERSION=latest make submodules -j3 || make submodules -j1

# Regenerate liberty timing files for all corners
make timing
```

--------------------------------

### 1.8V PMOS FET Device Instantiation

Source: https://context7.com/google/skywater-pdk/llms.txt

SPICE model parameters and instantiation examples for the 1.8V PMOS transistor, including a NAND gate example.

```spice
* Available PMOS variants:
*   sky130_fd_pr__pfet_01v8     - Standard threshold
*   sky130_fd_pr__pfet_01v8_lvt - Low threshold voltage
*   sky130_fd_pr__pfet_01v8_hvt - High threshold voltage

* Operating Voltages:
*   V_DS = 0 to -1.95V
*   V_GS = 0 to -1.95V
*   V_BS = -0.1 to +1.95V

* Example: CMOS NAND gate
.subckt nand2 a b y vdd vss
* Pull-up network (PMOS in parallel)
Mp1 y a vdd vdd sky130_fd_pr__pfet_01v8 W=0.84 L=0.15
Mp2 y b vdd vdd sky130_fd_pr__pfet_01v8 W=0.84 L=0.15
* Pull-down network (NMOS in series)
Mn1 y a n1 vss sky130_fd_pr__nfet_01v8 W=0.42 L=0.15
Mn2 n1 b vss vss sky130_fd_pr__nfet_01v8 W=0.42 L=0.15
.ends nand2
```

--------------------------------

### 1.8V NMOS FET Device Instantiation

Source: https://context7.com/google/skywater-pdk/llms.txt

SPICE model parameters and instantiation examples for the 1.8V NMOS transistor.

```spice
* SPICE Model: sky130_fd_pr__nfet_01v8
* Operating Voltages:
*   V_DS = 0 to 1.95V
*   V_GS = 0 to 1.95V
*   V_BS = +0.3 to -1.95V

* Basic NMOS instantiation
M1 drain gate source body sky130_fd_pr__nfet_01v8 W=0.42 L=0.15

* Example: Simple inverter
.subckt inv in out vdd vss
M1 out in vss vss sky130_fd_pr__nfet_01v8 W=0.42 L=0.15
M2 out in vdd vdd sky130_fd_pr__pfet_01v8 W=0.84 L=0.15
.ends inv
```

--------------------------------

### Initialize PDK and Generate Liberty Files

Source: https://github.com/google/skywater-pdk/blob/main/README.src.rst

Commands to download standard cell libraries and regenerate timing files. Note that the submodule download is approximately 7GB.

```bash
# Expect a large download! ~7GB at time of writing.
SUBMODULE_VERSION=latest make submodules -j3 || make submodules -j1

# Regenerate liberty files
make timing
```

--------------------------------

### Check Versioning Format

Source: https://context7.com/google/skywater-pdk/llms.txt

Understand the semantic versioning scheme used for the PDK.

```text
Version format: vX.Y.Z-AAA-gHHHHH

v    - Literal 'v' prefix
X    - Milestone Release (0=alpha, 1=beta, 2=production)
Y    - Major Release Number
Z    - Minor Release Number
AAA  - Git commit count since tag
HHHHH - Git commit short hash

Examples:
  v0.0.1          - Alpha, initial release
  v0.20.1         - Alpha, major release 20, patch 1
  v1.0.0-15-gabc123 - Beta, 15 commits after v1.0.0
  v2.0.0          - Production ready

Get version in repository:
  git describe --tags
```

--------------------------------

### Generate Liberty Files via CLI

Source: https://context7.com/google/skywater-pdk/llms.txt

Use the command-line interface to generate timing files and list available corners.

```bash
# List available corners for a library
python -m skywater_pdk.liberty libraries/sky130_fd_sc_hd/latest

# Generate timing files for all corners
python -m skywater_pdk.liberty libraries/sky130_fd_sc_hd/latest all

# Generate with ccsnoise data
python -m skywater_pdk.liberty libraries/sky130_fd_sc_hd/latest all --ccsnoise

# Generate power leakage files (sky130_fd_sc_ms only)
python -m skywater_pdk.liberty libraries/sky130_fd_sc_ms/latest all --leakage

# Generate for specific corner with custom output directory
python -m skywater_pdk.liberty libraries/sky130_fd_sc_hd/latest tt_025C_1v80 \
    -o ./timing_output

# Enable debug output
python -m skywater_pdk.liberty libraries/sky130_fd_sc_hd/latest tt_025C_1v80 --debug
```

--------------------------------

### Download and Update PDK Submodules

Source: https://github.com/google/skywater-pdk/blob/main/README.rst

Use these commands to download or update to the latest version of all standard cell libraries and regenerate liberty files. Expect a large download size.

```bash
# Expect a large download! ~7GB at time of writing.
SUBMODULE_VERSION=latest make submodules -j3 || make submodules -j1
```

```bash
# Regenerate liberty files
make timing
```

--------------------------------

### Standard Cell Libraries Overview

Source: https://context7.com/google/skywater-pdk/llms.txt

Table of available foundry-provided standard cell libraries and their characteristics.

```text
Library           | VDD  | Description                    | Cell Height | Gate Density
------------------|------|--------------------------------|-------------|-------------
sky130_fd_sc_hd   | 1.8V | High Density                   | 2.72um      | 160k gates/mm²
sky130_fd_sc_hdll | 1.8V | High Density, Low Leakage      | 2.72um      | 120k gates/mm²
sky130_fd_sc_hs   | 1.8V | High Speed                     | 3.33um      | Compatible
sky130_fd_sc_ms   | 1.8V | Medium Speed                   | 3.33um      | Compatible
sky130_fd_sc_ls   | 1.8V | Low Speed                      | 3.33um      | Compatible
sky130_fd_sc_lp   | 1.8V | Low Power (~750 cells)         | 3.33um      | Compatible
sky130_fd_sc_hvl  | 5.0V | High Voltage                   | 4.07um      | 100k gates/mm²

Drop-in compatible: sky130_fd_sc_hs, sky130_fd_sc_ms, sky130_fd_sc_ls
```

--------------------------------

### Generate Liberty Files via Python API

Source: https://context7.com/google/skywater-pdk/llms.txt

Collect library data and generate Liberty timing files for specific corners.

```python
from skywater_pdk.liberty import collect, generate, TimingType

# Collect available corners and cells from a library
libdir = "libraries/sky130_fd_sc_hd/latest"
lib, corners, all_cells = collect(libdir)

print(f"Library: {lib}")              # sky130_fd_sc_hd
print(f"Corners: {list(corners.keys())[:5]}")  # ['ff_100C_1v65', ...]
print(f"Cells: {len(all_cells)}")     # Number of cells

# Generate liberty file for a specific corner
corner = "tt_025C_1v80"
corner_types, corner_cells = corners[corner]

# TimingType options:
#   TimingType.basic    - Standard timing
#   TimingType.ccsnoise - With CCS noise data
#   TimingType.leakage  - Power leakage data

generate(
    library_dir=libdir,
    lib=lib,
    corner=corner,
    ocorner_type=TimingType.basic,
    icorner_type=TimingType.basic,
    cells=corner_cells,
    output_directory="./output"
)
```

--------------------------------

### Library Naming Convention

Source: https://context7.com/google/skywater-pdk/llms.txt

Visual breakdown of the library naming scheme used in the PDK.

```text
sky130_fd_sc_hd
│      │  │  └── Library Name: hd (high density)
│      │  └───── Library Type: sc (standard cells)
│      └──────── Source: fd (SkyWater Foundry)
└─────────────── Process: sky130
```

--------------------------------

### PDK Copyright Notice

Source: https://github.com/google/skywater-pdk/blob/main/README.src.rst

Standard copyright and license header for PDK files.

```text
Copyright 2020 SkyWater PDK Authors

Licensed under the Apache License, Version 2.0 (the "License");
```

--------------------------------

### Path and Filename Parsing

Source: https://context7.com/google/skywater-pdk/llms.txt

Utilities for parsing cell paths and timing filenames to extract library and cell metadata.

```APIDOC
## parse_pathname

### Description
Parses a full file path to extract cell and library information.

### Parameters
- **path** (string) - Required - The full path to the cell file.

### Response
- **cell** (object) - The parsed cell object.
- **filename** (string) - The extracted filename.

## parse_filename

### Description
Parses a timing filename to extract cell name, extra metadata, and file extension.

### Parameters
- **filename** (string) - Required - The timing filename to parse.

### Response
- **cell** (object) - The cell object containing the name.
- **extra** (string) - Extra metadata string.
- **ext** (string) - The file extension.
```

--------------------------------

### Corner Parsing API

Source: https://context7.com/google/skywater-pdk/llms.txt

Extracts process corner information, including voltage, temperature, and flags, from filename strings.

```APIDOC
## parse_filename (Corners)

### Description
Extracts corner information from a filename string.

### Parameters
- **filename** (string) - Required - The filename containing corner information.

### Response
- **corner** (object) - The Corner object containing corner types, voltages, temperatures, and flags.
- **random** (any) - Additional parsed data.
```

--------------------------------

### Extract Corner Information

Source: https://context7.com/google/skywater-pdk/llms.txt

Parse process corner details, temperature, and flags from timing filenames.

```python
from skywater_pdk.corners import parse_filename, CornerType, CornerFlag

# Parse corner information from filename
corner, random = parse_filename('tt_1p80V_3p30V_3p30V_25C')
print(corner)
# Corner(corner=(CornerType.t, CornerType.t), volts=(1.8, 3.3, 3.3),
#        temps=(25,), flags=None)

# Parse with ccsnoise flag
corner, _ = parse_filename('sky130_fd_sc_ms__tt_1p80V_25C_ccsnoise.wrap.json')
print(corner.flags)   # (CornerFlag.ccsnoise,)

# Parse worst-case corners (wp=ff, ws=ss, wo=fs, wz=sf)
corner, _ = parse_filename('sky130_fd_sc_ms__wp_1p65V_n40C.wrap.json')
print(corner.corner)  # (CornerType.f, CornerType.f) - fast-fast

# CornerType values:
#   t = Typical
#   f = Fast
#   s = Slow

# Parse negative temperature
corner, _ = parse_filename('sky130_fd_sc_hd__ss_1p76V_n40C.cell.json')
print(corner.temps)   # (-40,)
```

--------------------------------

### Liberty File Generation

Source: https://context7.com/google/skywater-pdk/llms.txt

Collects library data and generates Liberty timing files for specific corners.

```APIDOC
## collect

### Description
Collects available corners and cells from a library directory.

### Parameters
- **libdir** (string) - Required - Path to the library directory.

## generate

### Description
Generates a Liberty timing file for a specific corner.

### Parameters
- **library_dir** (string) - Required - Path to the library.
- **lib** (string) - Required - Library name.
- **corner** (string) - Required - Corner identifier.
- **ocorner_type** (TimingType) - Required - Output timing type.
- **icorner_type** (TimingType) - Required - Input timing type.
- **cells** (list) - Required - List of cells to include.
- **output_directory** (string) - Required - Directory to save generated files.
```

--------------------------------

### Parse PDK Pathnames and Filenames

Source: https://context7.com/google/skywater-pdk/llms.txt

Extract cell and library information from file paths or timing filenames.

```python
# Parse a cell from full path
cell, filename = parse_pathname(
    'libraries/sky130_fd_sc_hd/v0.0.1/cells/a2111o/README.rst'
)
print(cell)
# Cell(name='a2111o', library=Library(..., version=LibraryVersion(0,0,1,...)))

# Parse a timing filename
cell, extra, ext = parse_filename(
    'sky130_fd_sc_hd__a2111o_4__ss_1p76V_n40C.cell.json'
)
print(cell.name)      # 'a2111o_4'
print(extra)          # 'ss_1p76V_n40C'
print(ext)            # 'cell.json'
```