Tiny Tapeout GF 26b · Die T26B on wafer.space Run 2
Neuromorphic PUF (distinct-tap LFSR arbiter + memristor XOR, GF180)
100 · Security · 1 × 2 tiles
by Prof. Santhosh Sivasubramani, IIT Delhi · repository @santhoshs93
Rendered from the layout at 0.33 µm per pixel. Layers: NwellDiffusionPolysiliconMetal 1Metal 2Metal 3Metal 4Metal 5Top metalPad openings
Logic density
| Core average logic cells per mm² | 17k (22% of buffer maximum) |
|---|---|
| Densest 0.1 mm square logic cells per mm² | 26k (35% of buffer maximum) |
| Core covered by logic | 55% |
| Transistor density transistors per mm² | 275k average, 344k in the 0.1 mm square with the most logic cells |
Every figure here is measured from the public layout, the same way for every design on the chip: see data and method, and how its designs used the process.
GF180mcuD digital Physical Unclonable Function: 8 distinct-tap maximal-length 10-bit LFSRs act as synthesizable virtual ring-oscillators, a 6-bit challenge selects a pair, and an arbiter FSM compares their popcounts over a programmable 2^N-cycle window (N in 4..12) to produce a response bit. 64 challenges accumulate into a 64-bit response that can be XORed with a host-loaded memristor vector for dual-entropy mode. SPI-programmable, IRQ output, 25 MHz signoff clock, 1x2 tile (upsized from 1x1: global-placement utilization 103.6% on 1x1).
Source repository Its page on Tiny TapeoutBuy a chip and board
| Size | 347 × 325 µm (0.113 mm²) |
|---|---|
| Macro | tt_um_santhosh_neuro_puf_gf |
| Files | documentation · licence · layout and netlist in Tiny Tapeout GF 26b |
| Tiles | 1 × 2 at column 6, row 10 of the tile grid |
| Mux address | 100 |
| Language | Verilog |
| Clock | 25 MHz |
| Built with | LibreLane 3.0.3, open_pdks 54435919abff |
| Transistors | 31,721 |
| Logic cells | 1,971 + 4,013 filler and tap cells |
| Libraries | 7t-5V (2k) |
| SRAM | No SRAM |
Process features
Which parts of the GF180MCU process this design uses: its transistor voltages and where they come from, its gate oxides, and any devices drawn by hand outside the standard cells, SRAM and pads.
| 5 V | 7t-5V standard cells |
|---|---|
| Gate oxides | Thick only (5 V/6 V) in the design itself |
Where the area went
How this project's area splits between logic cells, filler and tap cells and other.
- Logic cells 0.06 mm² (55%)
- Filler and tap cells 0.04 mm² (39%)
- Other 0.01 mm² (7%)
Most used cells
The ten standard cells this design uses most.
| Cell | Library | Instances | What it does |
|---|---|---|---|
| dffrnq_1 | 7t-5V | 308 | D flip-flop with reset |
| nand2_1 | 7t-5V | 175 | 2-input NAND gate |
| clkinv_1 | 7t-5V | 140 | Clock inverter |
| aoi22_1 | 7t-5V | 135 | AND-OR-Invert (2x2 inputs) |
| dlyb_1 | 7t-5V | 127 | Delay buffer |
| mux2_2 | 7t-5V | 107 | 2-input multiplexer (2x drive) |
| buf_2 | 7t-5V | 106 | Buffer (2x drive) |
| oai21_1 | 7t-5V | 72 | OR-AND-Invert compound gate |
| oai31_1 | 7t-5V | 71 | OR-AND-Invert compound gate |
| clkbuf_2 | 7t-5V | 70 | Clock buffer (2x drive) |
Logic density map
Logic cells per mm² in each 0.1 mm square of the project (counted in the square, scaled up to a mm²). Hatched outlines are SRAM macros; the red outline is the densest 0.1 mm square that avoids them (26k logic cells per mm²), found by sliding a 0.1 mm square over the project in 20 µm steps, so it can straddle the fixed squares and find more than any one of them. Squares at the edges are partial, so they read low.
Tiny Tapeout and wafer.space are independent companies that work together (announcement). Tiny Tapeout runs its own shuttles: it takes the projects, builds the die, and sells and supports the chips and boards. wafer.space has the dies manufactured on its GF180MCU runs, and these pages are wafer.space's measurements of them. For anything about a Tiny Tapeout project, chip or order, contact Tiny Tapeout.