Which open-source EDA tools power EcrioniX RTL-to-GDS Studio?

EcrioniX RTL-to-GDS Studio executes authentic open-source electronic design automation (EDA) tools: Icarus Verilog for functional simulation, Verilator for static RTL linting, Yosys for logic synthesis, OpenROAD for automated floorplanning, placement, clock tree synthesis, and routing, OpenSTA for signoff static timing analysis, and open-source SKY130 HD standard cell libraries.

What is the SkyWater SKY130 HD process design kit?

SkyWater SKY130 is the world's first open-source, commercially manufacturable 130nm CMOS technology platform developed by SkyWater Technology and Google. The High-Density (HD) variant provides standard cells optimized for compact digital density, making it the primary target for open-source silicon fabrication initiatives such as Google's Efabless ChipIgnite shuttles.

Can I inspect physical layouts, placements, and waveforms directly in the browser?

Yes! EcrioniX RTL-to-GDS Studio features native high-DPI HTML5 canvas visualizers for every design stage: an interactive VCD digital timing waveform viewer, an interactive SVG gate netlist schematic, an interactive floorplan viewer showing die/core margins and IO pins, an interactive placement viewer showing standard cell locations and density, an interactive routing viewer showing multi-metal interconnects (M1-M5), and a multi-layer layout viewer.

design.v

Design Architecture: Active Top Module

SkyWater SKY130 HD PDK (130nm)

SystemVerilog / Verilog Elaboration

This module is configured for synthesis using Yosys and physical place-and-route with OpenROAD. Standard cells will be mapped to sky130_fd_sc_hd standard cell primitives.

Target Clock

10.0 ns (100 MHz)

Core Utilization

55%

Interconnect Layers

5 Metals (met1-met5)

Yosys Synthesis & Technology Mapping Report

// Synthesis report will appear here upon flow execution.

OpenSTA Signoff Static Timing Analysis

// Static timing report will appear here after flow execution.

Design Rule Checking (DRC) Verification Magic / KLayout 130nm Rules

// DRC physical verification report will appear here.

Layout Versus Schematic (LVS) Verification Netgen Device Isomorphism

// LVS circuit equivalence report will appear here.

Final GDSII Mask Layout

Shortcut	Action
`Ctrl + Enter`	Run ASIC Physical Design Flow
`Ctrl + S`	Download Active Verilog File
`Ctrl + F`	Find & Replace in Code Editor
`Ctrl + B`	Toggle Project Explorer Sidebar
`Escape`	Close Modals / Dismiss Find Bar

🚀 Open-Source ASIC Implementation

Online RTL to GDSII Studio – Free Open-Source ASIC Design & Physical Implementation Flow

Q: What is the digital RTL-to-GDSII flow in ASIC design?

The RTL-to-GDSII flow is the end-to-end semiconductor design process that transforms high-level behavioral hardware code (Verilog or SystemVerilog) into a physical, manufacturable tapeout layout format (GDSII). The flow spans logic synthesis, technology mapping, floorplanning, power distribution networking, global and detailed placement, clock tree synthesis (CTS), global and detailed routing, parasitic extraction, static timing analysis (STA), physical verification (DRC and LVS), and final GDS stream-out.

Synthesize, place, route, and signoff digital integrated circuits entirely in your browser. Powered by Yosys, OpenROAD, OpenSTA, Verilator, and SkyWater SKY130 HD open-source semiconductor technology.

Autonomous EDA Stages

130 nm

SkyWater HD Cell Library

100%

True Open-Source Toolchain

0 Install

Instant Cloud Execution

1. Understanding the Modern RTL to GDSII Implementation Flow

In digital application-specific integrated circuit (ASIC) design, the journey from architectural specification to manufactured silicon is known as the RTL-to-GDSII flow. At the entry point, digital designers formulate logic behavior using Register-Transfer Level (RTL) Hardware Description Languages (HDLs) such as SystemVerilog or Verilog. At the terminal point lies GDSII (Graphic Database System II) or OASIS format—a binary file describing geometric polygon masks transferred to lithography scanners at the semiconductor foundry.

Historically, mastering physical design required expensive proprietary Electronic Design Automation (EDA) licenses from Cadence, Synopsys, or Siemens EDA, alongside dedicated high-performance Linux compute clusters. EcrioniX RTL-to-GDS Studio democratizes this workflow by executing authenticated, real-world open-source EDA binaries (Yosys, OpenROAD, OpenSTA, Verilator, Icarus Verilog) within containerized cloud sandboxes, streaming detailed layout geometry, timing histograms, and DRC/LVS reports directly to your browser in real time.

The 17 Comprehensive Physical Design Stages

Every design submitted to the EcrioniX ASIC backend progresses through an industry-standard sequence of synthesis, physical synthesis, place-and-route (P&R), parasitic extraction, and static timing signoff:

01. RTL Syntax & Elaboration

Validates SystemVerilog/Verilog lexical correctness, resolves parameterized module hierarchies, binds generate blocks, and checks port widths.

02. Verilator RTL Linting

Static code analysis detecting combinatorial loops, unclocked latches, implicit bit-width truncation, unused net declarations, and synthesis-simulation mismatches.

03. Logic Simulation & VCD Waveforms

Executes testbench stimuli using Icarus Verilog (iverilog/vvp). Dumps IEEE 1364 Value Change Dump (VCD) transitions rendered dynamically on the built-in waveform viewer.

04. Logic Synthesis (Yosys)

Transforms behavioral Verilog AST into a Generic Technology (GTECH) netlist. Performs constant propagation, dead-code elimination, and Boolean optimization (AIG minimization).

05. Technology Mapping (SKY130 HD)

Maps GTECH gates to concrete SkyWater 130nm High-Density standard cells (NAND2_1, NOR2_1, DFF_1, MUX2_1) using Liberty timing models and ABC mapping algorithms.

06. Chip Floorplanning

Establishes die aspect ratio, core boundary, halo margins, target target utilization (30%–70%), routing tracks for each metal layer (met1–met5), and peripheral I/O pin placements.

07. Power Distribution Network (PDN)

Synthesizes robust VDD and VSS power delivery grids consisting of met4/met5 vertical/horizontal stripes and met1 followpins to prevent IR drop and electromigration (EM).

08. Global Placement (RePlAce)

Analytic electrostatics-based placement solving Poisson equations to minimize Half-Perimeter Wirelength (HPWL) while dispersing cell density smoothly across the core.

09. Detailed Placement & Legalization

Aligns floating standard cells onto discrete manufacturing site rows, guarantees minimum spacing rules, resolves overlapping pins, and snaps instances to legal grid coordinates.

10. Clock Tree Synthesis (TritonCTS)

Constructs an impedance-matched H-tree or multi-corner clock buffer tree to deliver clock signals to all sequential registers with minimal insertion delay and skew.

11. Post-CTS Timing Repair

Inserts delay buffers into fast datapaths violating hold-time margins ($T_h$), resizes weak driving gates on setup-critical paths, and resolves max capacitance/slew violations.

12. Global Routing (FastRoute)

Coarse 3D routing dividing the chip into GCells. Evaluates congestion hot-spots, distributes wire capacity across routing layers, and generates guide files for detailed routing.

13. Detailed Routing (TritonRoute)

Realizes physical metal segments and vias (via1 through via4) adhering to strict design rules (DRC: minimum width, spacing, end-of-line spacing, via enclosure).

14. Parasitic Extraction (OpenRCX)

Extracts parasitic resistance ($R$) and capacitance ($C$) from routed polygon geometries into standard SPEF (Standard Parasitic Exchange Format) files.

15. Signoff STA (OpenSTA)

Computes true post-layout setup and hold slacks using SPEF back-annotation, worst-case operating corners, and SDC timing constraints. Reports critical paths with pico-second accuracy.

16. Physical Verification (DRC & LVS)

Validates that physical metal geometries comply with foundry design rules (DRC) and that the extracted layout netlist matches the structural synthesis netlist (LVS).

17. Final GDSII & DEF Stream-Out

Streams out complete manufacturing layout files (GDSII binary and DEF ASCII). Generates interactive vector layout previews ready for foundry tapeout or packaging.

2. Industry Platform Comparison: Open-Source vs Commercial EDA

How does EcrioniX RTL-to-GDS Studio compare against traditional commercial ASIC suites and existing online educational portals?

Feature / Capability	EcrioniX RTL-to-GDS Studio	EDA Playground	Commercial EDA (Cadence / Synopsys)
Full ASIC P&R Flow	✔ Yes (Floorplan to GDSII)	✖ Simulation & Synthesis only	✔ Full Flow (Innovus, ICC2)
Software License Cost	100% Free & Open-Source	Free Tier / Academic	$50,000–$500,000+ / seat
Installation Requirements	Zero (Runs in any modern browser)	Zero (Browser)	Dedicated RHEL Linux cluster + FlexLM
Underlying Engines	Yosys, OpenROAD, OpenSTA, Verilator	Icarus, Verilator, Yosys (Sim/Synth)	Genus, Innovus, DC, ICC2, PrimeTime
PDK Technology	SkyWater SKY130 HD (130nm open PDK)	Generic ASIC / Target FPGA only	Commercial TSMC/Samsung/Intel PDKs
Interactive Layout Viewer	Built-in Canvas (Zoom/Pan/Layers)	No layout visualization	Desktop GUI (Innovus / Calibre)
Static Timing Signoff	OpenSTA (SPEF back-annotated)	None	PrimeTime / Tempus (SPEF signoff)
Real File Exports	GDSII, DEF, SPEF, SDC, Netlist, VCD	Console log, limited VCD	Full foundry deliverables

3. Frequently Asked Questions (ASIC Physical Design & Studio Guide)

What is the RTL to GDSII flow in digital ASIC design? ▾

The RTL to GDSII flow is the end-to-end engineering pipeline that translates high-level Hardware Description Language (HDL) code—such as SystemVerilog or Verilog—into microscopic geometric layout data formatted as GDSII or OASIS files. These stream files encode the precise lithographic mask patterns required by a semiconductor foundry to manufacture functional microchips. Key phases include behavioral verification, logic synthesis, technology mapping, floorplanning, placement, clock tree synthesis (CTS), global and detailed routing, parasitic extraction, and signoff static timing analysis (STA).

How does EcrioniX RTL-to-GDS Studio run in the browser without local software? ▾

The studio connects client-side web interfaces with an asynchronous containerized cloud backend hosted on Hugging Face Spaces Docker infrastructure. When you trigger "Run Flow", the frontend dispatches your SystemVerilog code, timing constraints, and physical design parameters to our REST API v1. The containerized backend invokes authentic open-source EDA binaries (Yosys, OpenROAD, OpenSTA, Verilator) in an isolated Linux sandbox, parses intermediate DEF and GDSII files into lightweight vector structures, and streams real-time stage progress, log messages, and interactive layout coordinates directly to your browser canvas.

Which technology node and standard cell library does the studio use? ▾

The platform uses the production-proven SkyWater SKY130 HD (High Density) 130nm open-source PDK. The library comprises over 440 optimized standard cells, including combinational logic gates (NAND, NOR, XOR, AOI, OAI), sequential storage elements (positive-edge D flip-flops, scan flip-flops, latches), tri-state buffers, tie-high/tie-low cells, clock tree inverters, and decap filler cells. Standard cells have a uniform height of 2.72 μm, enabling automated row placement across 5 backend metal interconnect layers (met1 through met5).

What open-source EDA tools power the backend flow? ▾

The studio harnesses a suite of leading open-source electronic design automation tools:

Yosys: Open-source framework for Verilog RTL synthesis and logic optimization.
OpenROAD: Autonomous physical design engine managing floorplanning, PDN, placement, CTS, and routing.
OpenSTA: Gate-level static timing verifier computing path slack and setup/hold margins.
Verilator: High-performance SystemVerilog linter and behavioral simulator.
Icarus Verilog: IEEE 1364 compliance simulator for functional testbench verification.

Can I download the generated GDSII, DEF, and Verilog netlists? ▾

Yes! Once physical design completes, the "Export" dropdown menu on the top toolbar allows instant downloading of individual artifacts:

GDSII Stream File: Binary mask geometry ready for KLayout inspection or foundry submission.
DEF Layout File: Standard Design Exchange Format capturing die boundaries, pin placements, and cell coordinates.
Synthesized Verilog Netlist: Structural gate-level netlist mapped to SKY130 HD library primitives.
SPEF Parasitics: Extracted RC wire parasitics for post-layout signoff STA.
Timing SDC Constraints: Clock definitions and I/O delay specifications.

What is the difference between global placement and detailed placement? ▾

Global Placement treats standard cells as continuous movable points within the core area, solving global objective functions (such as analytical wirelength and cell density electrostatics) to prevent congestion hot spots. In global placement, cells often overlap and float between rows. Detailed Placement (Legalization) then snaps each cell to a valid manufacturing grid site row, resolves overlap conflicts, ensures proper N-well continuity, and satisfies design rule checks (DRC) while attempting to keep wirelength minimal.

Why is Clock Tree Synthesis (CTS) essential in digital ASIC design? ▾

In synchronous digital circuits, thousands of sequential flip-flops must receive the rising clock edge at nearly the exact same instant. Because wires introduce RC resistance and capacitance, driving all registers directly from an input pin would cause massive clock skew and slew degradation, causing fatal hold-time and setup-time timing violations. Clock Tree Synthesis constructs an automated, balanced buffer tree (typically an H-tree) with symmetric path lengths and buffer sizing, guaranteeing that clock arrival skew between launch and capture registers remains within tight picosecond bounds.

How does static timing analysis (STA) calculate setup and hold slack? ▾

Static timing analysis evaluates all timing paths without applying test vectors. For Setup Time ($T_{setup}$):

Setup Slack = Required Arrival Time - Data Arrival Time = (T_clk - T_{setup} - T_{uncertainty} + T_{capture_latency}) - (T_{launch_latency} + T_{cq} + T_{comb_delay})

.
A positive setup slack indicates the circuit will operate reliably at the target frequency.
For Hold Time ($T_{hold}$):

Hold Slack = Data Arrival Time - Required Arrival Time = (T_{launch_latency} + T_{cq} + T_{comb_delay}) - (T_{capture_latency} + T_{hold} + T_{uncertainty})

.
A negative hold slack represents a catastrophic race condition where new data overwrites existing state before the capture flip-flop latches it.

What are DRC and LVS checks in physical verification? ▾

DRC (Design Rule Checking) verifies that physical geometric shapes on every mask layer adhere to the foundry's minimum manufacturing tolerances (minimum wire width, spacing between parallel lines, via enclosure rules, antenna ratios). LVS (Layout Versus Schematic) extracts an electrical transistor circuit directly from the drawn layout polygons and performs formal graph isomorphism against the synthesized gate-level netlist to ensure no missing connections, shorts, or opens were created during routing.

How does OpenROAD perform power distribution network (PDN) planning? ▾

The Power Distribution Network (PDN) distributes clean VDD supply and VSS ground rails across the entire core area. OpenROAD synthesizes a low-impedance power mesh by creating wide horizontal and vertical metal stripes across upper metal layers (met4 and met5), connecting them via dense via arrays down to met1 standard-cell power rails (followpins). This low-resistance grid minimizes dynamic IR drop and prevents electromigration failures during high-frequency clock switching.

Can I write custom SystemVerilog code and run the physical flow? ▾

Yes! You can edit code directly in the integrated code editor, paste your own synthesizable Verilog or SystemVerilog modules, adjust target clock periods and placement core densities, and execute the entire 17-stage implementation flow. EcrioniX RTL-to-GDS Studio handles module elaboration and synthesis autonomously.

How are layout coordinates visualized in the browser canvas? ▾

Rather than streaming heavy binary files over the network, the backend DEF parser transforms placement and routing coordinates into an optimized vector JSON payload (`layout.json`). The client-side HTML5 canvas engine renders die boundaries, standard cell boxes, I/O pin ports, and multi-layer metal routes with high-performance 60-FPS hardware-accelerated transforms. Interactive controls support smooth pan, wheel zoom, mouse crosshairs, and live cell instance inspection on hover.

Is EcrioniX RTL-to-GDS Studio free to use for students and engineers? ▾

Yes. EcrioniX RTL-to-GDS Studio is completely free to use for students, educators, academic researchers, and semiconductor professionals worldwide. No credit card, account registration, or commercial license servers are required.

How does this studio integrate with the EcrioniX Verilog Simulator and VLSI learning platform? ▾

EcrioniX RTL-to-GDS Studio is seamlessly integrated into the EcrioniX semiconductor learning ecosystem. You can prototype and debug your RTL functionally in the EcrioniX Verilog Simulator, study microarchitectures in our processor studios, and transition directly to RTL-to-GDS Studio for complete physical layout tapeout and signoff static timing analysis.

4. Explore Connected EcrioniX VLSI & Computer Architecture Studios

EcrioniX provides a suite of interactive, browser-based engineering simulators and professional reference guides for digital VLSI, embedded systems, and computer engineering:

⚡

EcrioniX Verilog Studio

Interactive RTL simulator, real-time VCD waveform viewer, synthesis netlist schematic, and linting engine.

🧠

ARM Cortex-M3 Studio

Thumb-2 assembly editor, pipeline visualizer, virtual breadboard with GPIO LEDs, and NVIC interrupt simulator.

📟

8051 Microcontroller Studio

Step-by-step 8051 assembly execution, live register viewer, SFR inspection, and virtual peripheral board.

🚀

PCIe Architecture Learning Hub

Comprehensive guide to PCI Express Gen 1 through Gen 7, TLP packet structures, LTSSM state machine, and SerDes.