Study on Single Event Transients in Amplifier for Switched-Capacitor Circuits in CMOS Technology

This article presents a comprehensive analysis of the sensitivity of different switched-capacitor amplifier circuits to Single Event Transients (SETs). SETs are temporary variations in circuit output voltage or current caused by the interaction of heavy ions or high-energy protons with sensitive device nodes. The study focuses on three types of amplifier circuits commonly used in Multiplying Digital-to-Analog Converter (MDAC) stages of state-of-the-art pipelined ADCs: operational amplifier (Op-Amp) MDACs, comparator-based switched-capacitor (CBSC) MDACs, and ring amplifier (RAMP) based MDACs. By employing a TCAD-calibrated double exponential transient current pulse model, we simulate the SET responses resulting from heavy ion strike experiments on sensitive nodes of each MDAC type. Our analysis and simulations reveal the amplitude and recovery time of the output results for each MDAC type when subjected to SETs. Notably, we propose a novel radiation hardening solution: the parallel-auxiliary ring amplifier (PA-RAMP) structure, which demonstrates significantly better tolerance to SETs compared to other designs. This research not only contributes to the understanding of SET effects on analog switched-capacitor amplifier circuits but also introduces a cost-effective approach to mitigate these effects. As technology nodes scale down and circuits become more susceptible to SETs, the PA-RAMP structure offers a promising solution for radiation-hardened applications, enabling the use of scaling-friendly RAMPs with enhanced tolerance to SETs.