{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,8]],"date-time":"2026-02-08T21:23:46Z","timestamp":1770585826336,"version":"3.49.0"},"reference-count":34,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2020,11,22]],"date-time":"2020-11-22T00:00:00Z","timestamp":1606003200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This research introduces a new multifunction biquad filter based on voltage mode (VM) current-feedback operational amplifier (CFOA) and a fully uncoupled quadrature oscillator (QO) based on the proposed VM multifunction biquad filter. The proposed VM multifunction biquad filter has high impedance to the input voltage signal, and uses three CFOAs as active components, while using four resistors and two grounded capacitors as passive components. The VM CFOA-based multifunction biquad filter realizes band-reject, band-pass, and low-pass transfer functions at high-input impedance node simultaneously, which has the feature of easy cascading in VM operation without the need for additional voltage buffers. Additionally, the filter control factor parameter pole frequency (\u03c9o) and quality factor (Q) of the proposed VM multifunction biquad filter can be independently set by varying different resistors. By slightly modifying the VM multifunction biquad filter topology, a VM fully-uncoupled QO is easily obtained. The difference from the previous VM CFOA-based multifunction biquad filter is that the proposed VM CFOA-based multifunction biquad filter can be independently controlled by the filter control factor parameters, \u03c9o and Q. The proposed VM CFOA-based multifunction biquad filter can be transformed into a VM QO with fully-uncoupled adjustable of the oscillation condition and the oscillation frequency. The oscillation condition and the oscillation frequency can be fully-uncoupled and controlled by varying two sets of completely different resistors. The proposed VM fully-uncoupled QO solves the amplitude instability. The constant amplitude ratio of two quadrature sinusoidal waveforms can be realized when tuning FO. PSpice simulation and experimental results prove the performances of the proposed VM multifunction filter and VM fully-uncoupled QO. Simulation and experimental results confirm the theoretical analysis of the proposed circuits.<\/jats:p>","DOI":"10.3390\/s20226681","type":"journal-article","created":{"date-parts":[[2020,11,23]],"date-time":"2020-11-23T01:28:48Z","timestamp":1606094928000},"page":"6681","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Voltage-Mode Multifunction Biquad Filter and Its Application as Fully-Uncoupled Quadrature Oscillator Based on Current-Feedback Operational Amplifiers"],"prefix":"10.3390","volume":"20","author":[{"given":"San-Fu","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Electronic Engineering, National Chin-Yi University of Technology, Taiping, Taichung 41170, Taiwan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2666-2304","authenticated-orcid":false,"given":"Hua-Pin","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan"}]},{"given":"Yitsen","family":"Ku","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, California State University Fullerton, Fullerton, CA 92831, USA"}]},{"given":"Ming-Xiu","family":"Zhong","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"320","DOI":"10.3390\/app5030320","article-title":"Synthesis of cascadable DDCC-based universal filter using NAM","volume":"5","author":"Tran","year":"2015","journal-title":"Appl. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Herencsar, N., Koton, J., and Hanak, P. (2017). Universal voltage conveyor and its novel dual-output fully-cascadable VM APF application. Appl. Sci., 7.","DOI":"10.3390\/app7030307"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Safari, L., Barile, G., Ferri, G., and Stornelli, V. (2019). A new low-voltage low-power dual-mode VCII-based SIMO universal filter. Electronics, 8.","DOI":"10.3390\/electronics8070765"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Wang, S.F., Chen, H.P., Ku, Y., and Lin, Y.C. (2019). Versatile tunable voltage-mode biquadratic filter and its application in quadrature oscillator. Sensors, 19.","DOI":"10.3390\/s19102349"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"482","DOI":"10.3390\/app4040482","article-title":"Derivation of oscillators from biquadratic band pass filters using circuit transformations","volume":"4","author":"Wang","year":"2014","journal-title":"Appl. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Sotner, R., Jerabek, J., Langhammer, L., and Dvorak, J. (2018). Design and analysis of CCII-Based oscillator with amplitude stabilization employing optocouplers for linear voltage control of the output frequency. Electronics, 7.","DOI":"10.3390\/electronics7090157"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Ullah, F., Liu, Y., Li, Z., Wang, X., Sarfraz, M.M., and Zhang, H. (2018). A bandwidth-enhanced differential LC-voltage controlled oscillator (LC-VCO) and superharmonic coupled quadrature VCO for K-band applications. Electronics, 7.","DOI":"10.3390\/electronics7080127"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"M\u00e1rquez, A., P\u00e9rez-Bail\u00f3n, J., Calvo, B., Medrano, N., and Mart\u00ednez, P.A. (2018). A CMOS self-contained quadrature signal generator for SoC impedance spectroscopy. Sensors, 18.","DOI":"10.3390\/s18051382"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Jaikla, W., Adhan, S., Suwanjan, P., and Kumngern, M. (2020). Current\/voltage controlled quadrature sinusoidal oscillators for phase sensitive detection using commercially available IC. Sensors, 20.","DOI":"10.3390\/s20051319"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Wang, S.F., Chen, H.P., Ku, Y., and Lee, C.L. (2020). Versatile voltage-mode biquadratic filter and quadrature oscillator using four OTAs and two grounded capacitors. Electronics, 9.","DOI":"10.3390\/electronics9091493"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1016\/j.aeue.2004.11.027","article-title":"A 22.5 MHz current-mode KHN biquad using differential voltage current conveyor and grounded passive element","volume":"59","author":"Ibrahim","year":"2005","journal-title":"AEU Int. J. Electron. Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1109\/19.392891","article-title":"New current-feedback amplifier-based universal biquadratic filter","volume":"44","author":"Liu","year":"1995","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1109\/19.872927","article-title":"New configuration for realizing universal voltage-mode filter using two current-feedback amplifiers","volume":"49","author":"Horng","year":"2000","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1080","DOI":"10.1016\/j.aeue.2008.08.006","article-title":"Single-resistance-controlled quadrature oscillator and universal biquad filter using CFOAs","volume":"63","author":"Tangsrirat","year":"2009","journal-title":"AEU Int. J. Electron. Commun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1016\/j.aeue.2004.11.037","article-title":"Versatile voltage-mode CFA-based universal filter","volume":"59","author":"Shah","year":"2005","journal-title":"AEU Int. J. Electron. Commun."},{"key":"ref_16","first-page":"636","article-title":"CFA-based three input and two outputs voltage-mode universal filer","volume":"43","author":"Shan","year":"2005","journal-title":"Indian J. Pure Appl. Phy."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1299","DOI":"10.1109\/TCSII.2006.882345","article-title":"New universal biquads employing CFOAs","volume":"53","author":"Singh","year":"2006","journal-title":"IEEE Trans. Circuits Syst. II Express Briefs"},{"key":"ref_18","first-page":"87","article-title":"Voltage-mode universal biquad with five inputs and two outputs using two current feedback amplifiers","volume":"20","author":"Horng","year":"2013","journal-title":"Indian J. Eng. Mater. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2022","DOI":"10.1049\/el:19941416","article-title":"Voltage-mode notch, lowpass and bandpass filter using current-feedback amplifiers","volume":"30","author":"Chang","year":"1994","journal-title":"Electron. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1515\/FREQ.2005.59.11-12.264","article-title":"Multifunction filter using current feedback amplifiers","volume":"59","author":"Shah","year":"2005","journal-title":"Frequenz"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1167","DOI":"10.1007\/s00034-010-9194-4","article-title":"Multiple input single output universal biquad filter with current feedback operational amplifiers","volume":"29","author":"Nikoloudis","year":"2010","journal-title":"Circuits Syst. Signal Process."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1016\/j.aeue.2011.12.009","article-title":"Three-input single-output second-order filters using current-feedback amplifiers","volume":"66","author":"Topaloglu","year":"2012","journal-title":"AEU Int. J. Electron. Commun."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"232","DOI":"10.1587\/elex.2.232","article-title":"CFOA-based state-variable biquad and its high-frequency compensation","volume":"2","author":"Singh","year":"2005","journal-title":"IEICE Electron. Express"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"947","DOI":"10.1049\/el:19970618","article-title":"High input impedance voltage-mode lowpass, bandpass and highpass filter using current-feedback amplifiers","volume":"33","author":"Horng","year":"1997","journal-title":"Electron. Lett."},{"key":"ref_25","first-page":"278","article-title":"High input impedance voltage-mode lowpass, bandpass, highpass and notch filter using current feedback amplifiers","volume":"12","author":"Shan","year":"2005","journal-title":"Indian J. Eng. Mater. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1037","DOI":"10.1142\/S0218126605002787","article-title":"New high input impedance voltage-mode lowpass, bandpass and highpass filter using current feedback amplifiers","volume":"14","author":"Shan","year":"2005","journal-title":"J. Circuits Syst. Comp."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Wang, S.F., Chen, H.P., Ku, Y., and Chen, P.Y. (2019). A CFOA-based voltage-mode multifunction biquadratic filter and a quadrature oscillator using the CFOA-based biquadratic filter. Appl. Sci., 9.","DOI":"10.3390\/app9112304"},{"key":"ref_28","first-page":"265","article-title":"Applications of the current feedback operational amplifiers","volume":"11","author":"Soliman","year":"1996","journal-title":"Analog Integr. Circuits Process."},{"key":"ref_29","unstructured":"(2019, April 29). AD844: 60 MHz, 2000 V\/\u03bcs, Monolithic Op Amp with Quad Low Noise Data Sheet (Rev. G). Available online: www.linear.com."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1007\/s10470-012-9896-6","article-title":"New CFOA-based sinusoidal oscillators retaining independent control of oscillation frequency even under the influence of parasitic impedances","volume":"73","author":"Bhaskar","year":"2012","journal-title":"Analog Integr. Circuits Process."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"698","DOI":"10.1109\/81.526688","article-title":"Novel single-resistance-controlled-oscillator configuration using current-feedback-amplifiers","volume":"43","author":"Senani","year":"1996","journal-title":"IEEE Trans. Circuits Syst. I Fundam. Theory Appl."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2014","DOI":"10.1109\/TIM.2006.884139","article-title":"New CFOA-based single-element-controlled sinusoidal oscillators","volume":"55","author":"Bhaskar","year":"2006","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1883","DOI":"10.1109\/JSSC.2004.835828","article-title":"On the phase-noise and phase-error performances of multiphase LC CMOS VCOs","volume":"39","author":"Andreani","year":"2004","journal-title":"IEEE J. Solid-State Circuit"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"331","DOI":"10.1109\/4.494195","article-title":"A study of phase noise in CMOS oscillators","volume":"31","author":"Razavi","year":"1996","journal-title":"IEEE J. Solid State Circuits"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6681\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:35:45Z","timestamp":1760178945000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6681"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,22]]},"references-count":34,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["s20226681"],"URL":"https:\/\/doi.org\/10.3390\/s20226681","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,11,22]]}}}