Questa One

Questa One is the Siemens EDA smart verification portfolio for IC and FPGA design teams. It brings functional and fault simulation, static RTL checks (lint, CDC and RDC), stimulus-free formal verification, debug, verification management and agentic AI workflows under one brand, which Siemens announced on 13 May 2025.

In Siemens’ own words, Questa One is “the Siemens EDA smart verification solution powered by AI, purpose-built to address productivity gaps caused by increasing design complexities of 3DIC and chiplet-based architectures.” Siemens explains the name as being about “integrating flows, combining engines and unifying applications.” GSAS Micro Systems supplies Questa One in India, alongside Questa FPGA Essentials for teams whose work is FPGA simulation and lint.

What Is in Questa One

Siemens organises Questa One into product groups. The table maps each group to the job it does in a verification flow. Product names are Siemens’ own.

Questa One Simulation

Siemens describes the Questa One simulation suite as one that “unifies functional and fault simulation with integrated debugging to a single platform using a single database.” Questa One Sim is the functional simulator. Around it sit five targeted engines:

• Sim FX: scalable, concurrent fault simulation for functional safety, and functional fault grading for DFT.
• Sim CX: coverage acceleration through an advanced constraint solver.
• Sim DX: DFT pattern verification acceleration, built in partnership with Tessent.
• Sim Xact: formal analysis and flow automation to remove X-pessimism in gate-level simulation.
• Sim PA: power-aware simulation that checks planned power management early.

Siemens’ launch release, linked under References, reports its own performance results for these engines; ask us to walk through them against your designs during an evaluation.

Lint, CDC and RDC: Static RTL Verification

Lint and clock-domain crossing checks are where many Indian SoC and FPGA teams start. Siemens groups these tools as Questa Design Solutions, “an automated and integrated suite of verification tools for designers to improve initial RTL quality.”

• Questa Lint gives designers pre-configured methodologies that “provide immediate, intuitive feedback on design issues.”
• Questa CDC uses structural analysis to detect clock domains, synchronizers and low-power structures through the UPF, then generates assertions and metastability models for protocol and reconvergence verification. Siemens states it works from “only your RTL (and UPF power intent file).”
• Questa RDC does the same job for asynchronous reset domains.
• Questa Signoff CDC builds on the RTL CDC analysis to find glitches and other crossing issues.
• Questa Developer is an HDL design environment with continuous, on-the-fly linting and block-diagram visualisation, for FPGA and ASIC teams.

Formal Verification: Questa One SFV

Questa One SFV (stimulus-free verification) is Siemens’ static and formal suite, providing “over 20 stimulus-free analyses.” Its apps include Formal Inspection for automatic issue hunting, Property Verification for exhaustive proofs, Connectivity Analysis, Register Analysis against CSV or IP-XACT specifications, Security Analysis of paths to sensitive storage, RTL Equivalence between specification and implementation blocks, and X-Sensitivity Analysis. Siemens also lists Questa Increase Coverage and Questa Equivalent FPGA under the same heading.

Debug: Questa Visualizer

The Questa Visualizer Debug Environment supports, in Siemens’ words, “the complete logic verification flow including simulation, emulation, prototyping, testbench, low-power, and assertion analysis.” It provides synchronised waveform, source and connectivity views, UVM class and transaction debug, and time-cone and logic-cone windows that trace an unknown (X) value or an unexpected event back to its root cause.

Questa One Agentic Toolkit

Siemens announced the Questa One Agentic Toolkit on 27 February 2026. It launched with five agents:

• RTL Code Agent: generates synthesizable RTL from natural-language descriptions while checking for coding violations.
• Lint Agent: configures lint analysis and offers AI-assisted fixes or waivers for the designer to review.
• CDC Agent: configures and runs clock-domain crossing verification and suggests configuration changes.
• Verification Planning Agent: generates verification plans from design specifications, with the engineer approving each step.
• Debug Agent: correlates waveforms, assertions, coverage data and log files to speed root-cause analysis.

Siemens’ current Agentic Toolkit page describes the toolkit as a single Gateway plus five Flow Agents for planning, design, verification, debug and closure. Siemens states the toolkit works with coding applications including GitHub Copilot, Claude Code, Cursor, Cline and its own Fuse EDA AI System, and that it is “framework- and LLM-agnostic.” For how Siemens checks agent decisions against its verification engines, see Siemens Self-Verifying EDA AI Agents: What It Means for India.

Questa One vs Questa FPGA Essentials: Which Do You Need?

Both are Siemens products, and GSAS supplies both in India. Many teams start with the FPGA bundle and grow into Questa One as designs move towards ASIC.

Questa One and the Rest of the Siemens EDA Flow

Siemens positions Questa One alongside Tessent for DFT, and its launch release describes connected verification “across Siemens’ Questa One, Tessent DFT and Veloce CS emulation and prototyping systems.” For how simulation, emulation and FPGA prototyping divide the work, see our explainer on hardware emulation vs FPGA prototyping vs simulation. GSAS supplies Questa One and Tessent; Veloce hardware is outside the range GSAS supplies.

Buy Questa One in India from GSAS

GSAS Micro Systems is an authorized Siemens EDA partner in India and a value added distributor/reseller for Siemens EDA products. We have a dedicated FAE team ready to help you with custom built solutions matching your needs. Our application engineers work with verification teams in Bengaluru, Hyderabad, Chennai, Pune, Mumbai and Delhi NCR on:

• Scoping: matching Questa One products to your design size, flow and safety requirements.
• Evaluation: setting up a trial on a representative block from your own RTL.
• Methodology: lint and CDC rule setup, UVM testbench structure and coverage planning.
• Procurement: INR quotes with GST invoicing, and support for GeM, SAP Ariba and Coupa purchasing.

See the full Siemens EDA partner page for the rest of the line.

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References

• Siemens, Questa One smart verification solution
• Siemens, Questa One Simulation
• Siemens, Questa Design Solutions
• Siemens, Questa Clock-Domain Crossing
• Siemens, Questa Developer
• Siemens, Questa One stimulus-free verification
• Siemens, Questa Visualizer Debug Environment
• Siemens, Questa One Verification IQ
• Siemens, Questa One Agentic Toolkit
• Siemens press release, Siemens leverages AI to close industry’s IC verification productivity gap in new Questa One smart verification solution, 13 May 2025
• Siemens press release, Siemens accelerates integrated circuit design and verification with agentic AI in Questa One, 27 February 2026