Large Language Models (LLMs) are entering every stage of electronic system development, and digital design was the first beneficiary. Frontier models now pass roughly 90% of standard register-transfer level (RTL) generation benchmarks, an agentic system has designed a complete RISC-V core from a 219-word specification, and electronic design automation (EDA) vendors are shipping agentic assistants. Analog and mixed-signal design tells a different story. A recent three-tier evaluation of two frontier models on ten fundamental analog circuits found excellent reasoning, mixed implementation and catastrophic simulator syntax, with at best three of ten netlists compiling on the first run. This asymmetry defines the current frontier of AI-assisted chip design.
This tutorial presents a comprehensive picture of LLM-based circuit design on both sides of that divide, and introduces the closed-loop design agent as the remedy for the analog gap. In the beginning, the landscape of LLM-assisted chip design is surveyed. The three-tier evaluation framework is then presented as the one-shot baseline. The core of the tutorial is dedicated to closed-loop agentic workflows, in which the model proposes a circuit, a deterministic layer repairs the netlist, an open-source simulator measures it, and the model revises the design from the measured feedback. New results on an open-source 180 nm foundry process are presented, showing which failures the loop recovers tier by tier and testing the model's causal claims against the simulator, including a live demonstration of the design agent. Participants will gain a practical, evidence-based methodology for applying design agents to their own circuits.
Motivation and Relevance
Microelectronics is experiencing its third great boom, and this time artificial intelligence is both the driver and the customer. Numerous fields such as automotive, telecommunications, biomedical devices and data centers depend on chips whose complexity keeps growing while the pool of experienced designers does not. LLMs represent a paradigm shift in how engineers interact with specifications, design data and simulation environments. In digital design the progress is measurable and fast. A 2026 IEEE Access review of thirty-one published efforts reports that frontier models reach up to 89.7% on the VerilogEval benchmark and 96.1% on RTLLM when a lightweight reflection loop is added, and an agentic system recently produced VerCore, the first complete RISC-V CPU core designed autonomously by AI agents, verified in simulation at 1.48 GHz. Commercial agentic tools are entering production EDA flows.
Yet despite this momentum, analog and mixed-signal design remains the hardest target for automation and the domain where the talent shortage is felt most sharply. Analog knowledge is largely tacit, the feedback is numeric rather than textual, and a single syntax mistake silently invalidates an otherwise sound design. The speaker's three-tier evaluation of Claude Opus 4.1 and ChatGPT-5 on ten fundamental circuits, published at ETECOM 2025, quantified this precisely: strong analytical reasoning at the top, systematic biasing errors in the middle, and a catastrophic failure of simulator syntax at the bottom, where one model compiled zero of ten netlists even after cleanup. For design teams the consequence is a knowledge gap. It is presently unclear what these tools can be trusted with, what a feedback loop can recover, and which failures are fundamental. This uncertainty leads to misplaced expectations in both directions, from blanket rejection to uncritical adoption.
This tutorial addresses that knowledge gap with measured evidence. It builds directly on the speaker's published three-tier baseline (ETECOM 2025) and on his new closed-loop study, in which an un-augmented LLM agent iterates against the open-source ngspice simulator on the open GlobalFoundries 180 nm process, supported by a deterministic netlist repair layer and a simulator-grounded audit of the model's own reasoning. The complete workflow runs on open tools and public repositories, and hence every result shown in the tutorial can be reproduced by the participants without commercial licenses. The topic sits at the intersection of design automation, analog and mixed-signal circuits and engineering education, all central themes of the ICM community, and it addresses a question that every design group and every engineering classroom currently faces.
Tutorial Content
The tutorial is organized in five parts. The durations include short transitions and add up to a three-hour session.
Part 1: The Landscape of LLMs in Chip Design (35 min)
In the beginning an overview of LLM-assisted chip design is given, establishing how language models represent circuit knowledge and why chip design is a demanding target for them. The current research directions are then classified for both the digital and the analog domain, separating augmented approaches, namely retrieval, design databases and fine-tuning, from un-augmented baselines that rely on the model alone.
Topics: LLM fundamentals for circuit designers, in-context learning, agents and tools, taxonomy of current approaches, the analog/digital asymmetry
Part 2: The One-Shot Baseline (35 min)
The three-tier evaluation framework is presented, separating design reasoning, implementation competency and syntax proficiency. Results of Claude Opus 4.1 and ChatGPT-5 on ten fundamental analog circuits in an open 180 nm process are discussed in detail, including the sophistication paradox in which advanced testbenches are undermined by elementary syntax errors. The revived strength of equation- based design methods is examined, since it carries direct implications for analog design education.
Topics: three-tier framework, benchmark circuits, tier-by-tier results, failure taxonomy, implications for design methodology and education
Part 3: Closing the Loop with Design Agents (50 min)
The core of the tutorial is dedicated to the closed-loop design agent. The anatomy of the loop is presented step by step: the specification, the proposed circuit, a deterministic netlist repair layer, simulation, measurement, evaluation against the specification, diagnosis and revision. Deterministic repair is contrasted with the common practice of asking the model to regenerate on error. The recoverability of failures is then decomposed tier by tier, separating what iterative feedback recovers from what remains knowledge-bound. To close, a reasoning-validity audit is introduced in which the model's stated causal claims are tested against the simulator, so that evidence-driven design is separated from fortunate search. The session includes a live demonstration in which an open-source agent designs an operational transconductance amplifier to a gain, bandwidth and phase-margin specification on the open 180 nm process.
Topics: agent anatomy, deterministic netlist repair, iterative feedback, tier-wise recoverability, reasoning- validity audit, live demonstration
Part 4: The View from Digital Design (30 min)
The digital domain is then examined as the reference point. The state of RTL generation is summarized, followed by the VerCore case study, a complete RISC-V core produced by an agentic system from a 219- word specification in twelve hours. Commercial agentic EDA tools and their intended use are reviewed, together with the recurring digital failure modes. Since digital loops close more easily thanks to executable testbenches and reference models, the ingredients that analog design can import are identified explicitly.
Topics: RTL generation benchmarks, reflection loops, the VerCore case study, agentic EDA tools, recurring failure modes, lessons for mixed-signal teams
Part 5: Hybrid Workflows, Adoption and Outlook (30 min)
Finally, a practical adoption playbook is presented for design teams and educators: where the tools can be trusted, which outputs must be verified, and how agent reasoning should be logged and audited. Open problems are stated plainly, including layout, parasitics, process corners and silicon validation. The session concludes with the open repositories and an open discussion.
Topics: hybrid human-agent workflows, verification discipline, open problems, resources and repositories, discussion
Learning Outcomes
After completing this tutorial, participants will be able to:
- Explain how LLMs represent circuit design knowledge and where the analog/digital capability asymmetry originates.
- Apply the three-tier framework (reasoning, implementation, syntax) to evaluate any model on their own circuits.
- Describe the anatomy of a closed-loop design agent and the role of the deterministic netlist repair layer.
- Distinguish failures that iterative feedback recovers from failures that are knowledge-bound.
- Audit the causal reasoning of a design agent against simulation instead of taking its explanations on faith.
- Reproduce the complete workflow with open-source tools and public repositories, without commercial licenses.
Keywords:
Large Language Models, design agents, analog circuit design, mixed-signal design, RTL generation, EDA, SPICE, open-source PDK
