SPICED+: Syntactical Bug Pattern Identification and Correction of Trojans in A/MS Circuits Using LLM-Enhanced Detection

Analog and mixed-signal (A/MS) integrated circuits (ICs) are crucial in modern electronics, playing key roles in signal processing, amplification, sensing, and power management. Many IC companies outsource manufacturing to third-party foundries, creating security risks such as syntactical bugs and stealthy analog Trojans. Traditional Trojan detection methods, including embedding circuit watermarks and hardware-based monitoring, impose significant area and power overheads while failing to effectively identify and localize the Trojans. To overcome these shortcomings, we present SPICED+, a software-based framework designed for syntactical bug pattern identification and the correction of Trojans in A/MS circuits, leveraging large language model (LLM)-enhanced detection. It uses LLM-aided techniques to detect, localize, and iteratively correct analog Trojans in SPICE netlists, without requiring explicit model training, and thus incurs zero area overhead. The framework leverages chain-of-thought reasoning and few-shot learning to guide the LLMs in understanding and applying anomaly detection rules, enabling accurate identification and correction of Trojan-impacted nodes. With the proposed method, we achieve an average Trojan coverage of 93.3%, average Trojan correction rate of 91.2%, and an average false-positive rate of 1.4%.