Analog mixed-signal circuit sizing involves complex trade-offs within high-dimensional design spaces. Existing automatic analog circuit sizing approaches rely solely on netlists, ignoring the circuit schematic, which hinders the cognitive link between the schematic and its performance. Furthermore, the black-box nature of machine learning methods and hallucination risks in large language models fail to provide the necessary ground-truth explainability required for industrial sign-off. To address these challenges, we propose a Vision Language Model-optimized collaborative agent design workflow (VLM-CAD), which analyzes circuits, optimizes DC operating points, performs inference-based sizing, and executes external sizing optimization. We integrate Image2Net to annotate circuit schematics and generate a structured JSON description for precise interpretation by Vision Language Models. Furthermore, we propose an Explainable Trust Region Bayesian Optimization method (ExTuRBO) that employs collaborative warm-start from agent-generated seeds and offers dual-granularity sensitivity analysis for external sizing optimization, supporting a comprehensive final design report. Experiment results on amplifier sizing tasks using 180nm, 90nm, and 45nm Predictive Technology Models demonstrate that VLM-CAD effectively balances power and performance while maintaining physics-based explainability. VLM-CAD meets all specification requirements while maintaining low power consumption in optimizing an amplifier with a complementary input and a class-AB output stage, with a total runtime under 66 minutes across all experiments on two amplifiers.

翻译：模拟混合信号电路的尺寸优化涉及高维设计空间内的复杂权衡。现有自动模拟电路尺寸优化方法仅依赖网表，忽略了电路原理图，这阻碍了原理图与其性能之间的认知关联。此外，机器学习方法的黑箱特性以及大语言模型的幻觉风险，无法提供工业签核所需的基本事实可解释性。为应对这些挑战，我们提出一种视觉语言模型优化的协同智能体设计流程（VLM-CAD），该流程分析电路、优化直流工作点、执行基于推理的尺寸优化，并进行外部尺寸优化。我们集成Image2Net来标注电路原理图并生成结构化JSON描述，以供视觉语言模型进行精确解读。此外，我们提出一种可解释的信任域贝叶斯优化方法（ExTuRBO），该方法采用智能体生成种子的协同热启动，并为外部尺寸优化提供双粒度灵敏度分析，以支持生成全面的最终设计报告。基于180nm、90nm和45nm预测技术模型的放大器尺寸优化实验结果表明，VLM-CAD在保持基于物理解释性的同时，有效平衡了功耗与性能。在优化一个具有互补输入级和AB类输出级的放大器时，VLM-CAD满足了所有规格要求，同时保持了低功耗，且两个放大器的所有实验总运行时间低于66分钟。