Note: phase-locked loop with a voltage controlled oscillator based on a liquid crystal cell as variable capacitance Articles uri icon

publication date

  • December 2011

issue

  • 12 (126101)

volume

  • 82

international standard serial number (ISSN)

  • 0034-6748

electronic international standard serial number (EISSN)

  • 1089-7623

abstract

  • A phase-locked loop is demonstrated using a twisted-nematic liquid crystal cell as a capacitance that can be varied as a function of applied voltage. The system is formed by a phase detector, a low-pass filter, as well as a voltage controlled oscillator including such variable capacitance. A theoretical study is proposed and experimentally validated. Capture and locked ranges of hundreds of kHz have been obtained for the configuration used in this circuit. An application as frequency demodulator using a practical implementation of this circuit has been demonstrated.

keywords

  • demodulators; liquid crystal devices; low-pass filters; phase detectors; phase locked loops; phase locked oscillators; voltage-controlled oscillators