A compact, all-digital microwave impedance microscopy system with automatic baseline cancellation.

Abstract

We present a compact, fully digitally controlled microwave impedance microscopy (MIM) system implemented on a modular surface-mount platform. The design features a high-resolution, digitally tunable cancellation line that efficiently suppresses baseline reflections via destructive interference, thereby reducing noise and enhancing sensitivity for low baseband frequency or high power measurements. The physics-informed cancellation algorithm rapidly minimizes residual power within few seconds, requiring no manual adjustment. The quasi-DC-coupled readout supports both contact- and tapping-mode MIM imaging without risk of saturation. We validate system performance with high-quality MIM scans and demonstrate near-Johnson-noise-limited noise floor down to 4 kHz baseband frequency with optimal cancellation.