{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T11:02:42Z","timestamp":1753873362210,"version":"3.41.2"},"reference-count":22,"publisher":"AIP Publishing","issue":"1","funder":[{"DOI":"10.13039\/100000015","name":"DOE","doi-asserted-by":"publisher","award":["DE-FG02-06ER46346"],"award-info":[{"award-number":["DE-FG02-06ER46346"]}],"id":[{"id":"10.13039\/100000015","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2014,1,1]]},"abstract":"<jats:p>Non-contact scanning probe microscopy (SPM) has developed into a powerful technique to image many different properties of samples. The conventional method involves monitoring the amplitude, phase, or frequency of a cantilever oscillating at or near its resonant frequency as it is scanned across the surface of a sample. For high Q factor cantilevers, monitoring the resonant frequency is the preferred method in order to obtain reasonable scan times. This can be done by using a phase-locked-loop (PLL). PLLs can be obtained as commercial integrated circuits, but these do not have the frequency resolution required for SPM. To increase the resolution, all-digital PLLs requiring sophisticated digital signal processors or field programmable gate arrays have also been implemented. We describe here a hybrid analog\/digital PLL where most of the components are implemented using discrete analog integrated circuits, but the frequency resolution is provided by a direct digital synthesis chip controlled by a simple peripheral interface controller (PIC) microcontroller. The PLL has excellent frequency resolution and noise, and can be controlled and read by a computer via a universal serial bus connection.<\/jats:p>","DOI":"10.1063\/1.4862818","type":"journal-article","created":{"date-parts":[[2014,1,31]],"date-time":"2014-01-31T18:09:33Z","timestamp":1391191773000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":5,"title":["A hybrid analog-digital phase-locked loop for frequency mode non-contact scanning probe microscopy"],"prefix":"10.1063","volume":"85","author":[{"given":"M. M.","family":"Mehta","sequence":"first","affiliation":[{"name":"Northwestern University Department of Physics and Astronomy, , Evanston, Illinois 60208, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"V.","family":"Chandrasekhar","sequence":"additional","affiliation":[{"name":"Northwestern University Department of Physics and Astronomy, , Evanston, Illinois 60208, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"317","published-online":{"date-parts":[[2014,1,30]]},"reference":[{"key":"2023070317083319800_c1","doi-asserted-by":"crossref","DOI":"10.1007\/978-0-387-28668-6","volume-title":"Scanning Probe Microscopy","author":"Kalinin","year":"2007"},{"key":"2023070317083319800_c2","doi-asserted-by":"publisher","first-page":"3860","DOI":"10.1063\/1.1330225","volume":"77","year":"2000","journal-title":"Appl. Phys. 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