An Analog High-Speed Single-Cycle Lock-in Amplifier for Next Generation AFM Experiments

In this paper, we present a new architecture for analog amplitude demodulation in high-speed atomic force microscopy (AFM) applications. It features single-cycle capabilities and the possibility to work with elevated cantilever resonance frequencies up to 9 MHz. This latter feature is particularly important in view of the upcoming next generation of high resonance frequency cantilevers. As a proof-of-principle, we show a prototype of the proposed single-sideband upconversion architecture to be able to work with a conventional MultiMode 8 AFM system (Bruker) and a FastScan-A cantilever in air with f
_res≈
1.6 MHz. Overall, the presented lock-in amplifier with its improved demodulation speed will foster the research activities towards faster imaging speeds in AFM applications and thereby allow to further establish it as a tool for real-time studies of the dynamics of molecular and even atomic processes.