@article{oai:kanazawa-u.repo.nii.ac.jp:00040007,
 author = {福間, 剛士 and 淺川, 雅 and Fukuma, Takeshi and Yoshioka, Shunsuke and Asakawa, Hitoshi},
 issue = {7},
 journal = {Review of Scientific Instruments},
 month = {Jul},
 note = {We have developed a wideband phase-locked loop (PLL) circuit with real-time phase correction for high-speed and accurate force measurements by frequency modulation atomic force microscopy (FM-AFM) in liquid. A high-speed operation of FM-AFM requires the use of a high frequency cantilever which, however, increases frequency-dependent phase delay caused by the signal delay within the cantilever excitation loop. Such phase delay leads to an error in the force measurements by FM-AFM especially with a low Q factor. Here, we present a method to compensate this phase delay in real time. Combined with a wideband PLL using a subtraction-based phase comparator, the method allows to perform an accurate and high-speed force measurement by FM-AFM. We demonstrate the improved performance by applying the developed PLL to three-dimensional force measurements at a mica/water interface. © 2011 American Institute of Physics.},
 title = {Wideband phase-locked loop circuit with real-time phase correction for frequency modulation atomic force microscopy},
 volume = {82},
 year = {2011}
}