Varactor diode provides temperature stability for FM quadrature demodulator.
http://members.tripod.com/michaelgellis/quaddet.html
uses the phase-detector signals of a precision waveform-generator IC to perform FM demodulation.
http://www.edn.com/archives/1996/101096/21di_03.htm
generates a 55-MHz VHF signal.
http://www.edn.com/archives/1997/120497/25di_01.htm
used for generating a high quality FM stereo multiplex signal that is suitable for driving mono FM transmitters.
http://www.solorb.com/elect/fmst/