Quickstart

Install

With a current stable Rust toolchain and Cargo:

cargo install --git https://github.com/ucb-substrate/sram22 --locked sram22

Generate an SRAM

Create sram22.toml in a working directory:

[[sram]]
num_words = 64
data_width = 32
mux_ratio = 4
write_size = 8

Run the generator:

sram22

SRAM22 reads sram22.toml and writes GDS, LEF, SPICE, Verilog, and Liberty to build/sram22_64x32m4w8/ beside the configuration file. Add more [[sram]] blocks to generate several macros; each gets its own output subdirectory. A single configuration without the header is also accepted. To choose explicit paths:

sram22 --config sram22.toml --output-dir output

To simulate the macro in ngspice, load its .spice circuit netlist and the device-model library from your SKY130 PDK in a testbench. Select the corner with .lib, and provide power supplies, stimuli, and temperature. See the SPICE simulation example.

Command-line options

Option	Meaning
-c, --config <CONFIG>	TOML path; default sram22.toml
-o, --output-dir <OUTPUT_DIR>	Parent output directory; default build/ beside the config
-p, --parallel <PARALLEL>	Maximum concurrent macros; default no limit
-h, --help	Available options for the installed build
-V, --version	Version

The BWRC build offers --liberate for Liberate MX characterization, and --drc and --lvs for Calibre verification. A per-macro pex_level runs extraction. --all enables DRC/LVS; it uses interpolated timing unless --liberate is also supplied. Liberate uses extracted netlists when pex_level is set.

Liberty timing

Generation includes TT, SS, and FF Liberty files, such as sram22_64x32m4w8_tt_025C_1v80.lib, using interpolation by default. Timing data supports write_size = 8, word widths from 8 to 128 bits, and depths of 64, 128, 256, 512, 1024, or 2048 words. Both mux ratios are supported except 64 words with mux ratio 8. Other configurations need additional timing data or a BWRC build with --liberate. See the model assumptions.

The macro catalog provides characterized views for download.

Configuration reference

Option	Type	Required	Purpose
num_words	integer	yes	Number of words (depth) of the SRAM.
data_width	integer	yes	Word size in bits (width).
mux_ratio	4 or 8	yes	Column-mux ratio M: how many columns share one sense amplifier / write driver.
write_size	integer	yes	Write-mask granularity in bits. data_width must be an integer multiple of write_size.
pex_level	"r" | "c" | "rc" | "rcc"	no	Parasitic-extraction level. Only available on a commercial (BWRC) install; ignored otherwise.

Validity constraints

• num_words, data_width, and write_size must be positive; num_words must be a power of two.
• mux_ratio must be 4 or 8.
• data_width must be an integer multiple of write_size.
• The number of rows, num_words / mux_ratio, must be a power of two.
• At least 16 rows (num_words / mux_ratio ≥ 16).
• At least 16 columns (data_width · mux_ratio ≥ 16).
• pex_level, if set, must be one of "r", "c", "rc", or "rcc" (ignored without commercial plugins).

Derived quantities

• Number of rows = num_words / mux_ratio.
• Number of columns = data_width · mux_ratio.
• Address width = log2(num_words).
• Write-mask width = data_width / write_size.

Placement

Use the project's four supported quarter-turn placements: R90, R270, and their mirrors. Enforce this restriction in your flow; LEF symmetry alone does not enforce it. See Orientations, then the OpenROAD or Cadence integration outline.

Advanced setup

See the README for source builds and custom forks and BWRC installation.