Circuit design considerations for current preamplifiers for scanning tunneling microscopy

Current-to-voltage preamplifiers for scanning tunneling microscopy were tested side-by-side using a consistent testing protocol, to optimize performance and understand potential design trade-offs. Current-to-voltage gain and voltage noise density were measured as functions of frequency for two different circuit architectures: the feedback transimpedance amplifier and the current-shunt electrometer. The effect of specific component choices—of the integrated circuits, resistors, and capacitors—was also investigated.