Towards robust design of hybrid CMOS-SETs using feedback architectures

Low temperature operation and background charge fluctuation are among critical limitations for practical single-electron-tunneling (or SET) based circuits. Particularly, background charges on the island of SET devices affect the phase of Coulomb blockade oscillation, and may eventually lead to incorrect circuit operation. In order to construct robust SET circuits, we explore new design methods based on feedback architectures and novel characteristics of SET devices. We first discuss the impact of a direct feedback on circuit performance against background charges. Then, we propose a self-adapted input-referred feedback structure which can drastically reduce the sensitivity of circuit behaviors to background charge fluctuations. An improved hybrid CMOS-SET ADC circuit is also presented as an example to take advantage of the proposed feedback architecture for robustness against random background charges.