Digital Q control for enhanced measurement capability in cantilever-based instruments

摘要

A digital system for controlling the quality factor in a resonant device. The resonant device can be a a device that includes a cantilever within its system, such as an atomic force microscope. The quality factor can be digitally controlled to avoid noise effect in the analog components. A direct digital synthesizer implemented in a way that provides access to the output of the phase accumulator. That output is a number which usually drives a lookup table to produce a cosine or sine output wave. The output wave is created, but the number is also adjusted to form a second number that drives a second lookup table to create an adjustment factor to adjust the output from the cosine table. The adjusted digital signal than drives a DA converter which produces an output drive for the cantilever.