Searching for paper about Narrow band VCO using variable biasing (without varactor)

Hello! For fixed-frequency transistor and diode based oscillators it is possible to tune oscillating frequency by altering VCC.
Varactor is usefull for wide-band VCOs, there are many configurations: resonating stub on gate with varactor attached, coupled microstrip with varactor attached, etc. For narrow-band VCO there is interisting possibility of tuning frequency without varactor, using variable biasing of FET or voltage of diode. I will be happy to read something about doing it in right way, did not find any information yet!

update: found some interesting tutorial http://www.electroniq.net/radio-freq...modulator.html
good keyword varactorless

I think the frequency deviation will be very small with this method but it's possible.They marked that this configuration can be used for low voltage applications because of high voltage requirements of varactor diodes.It's true and false, because there are some varactor diodes working with 3V only.That's why, I prefer to use varactor based VCO instead this config. because changing bias point of the transistor will not guarantee frequency deviation inversily it will be depended on actual bias point that is temperature sensitive.

Have you searched on "Miller effect" ?
Frank