I saw it somewhere that for the LC circuit to oscillate it needs feedback and the feedback must be greater than the unity. I want explanation on what this mean and the component responsible for the feedback. Thanks
Hi,
That statement is a general statement that says something about getting
a real world LC oscillator to keep oscillating. In theory, a perfect LC
tank will oscillate indefinitely because there is no energy loss. In the
real world however, the inductor absorbs some energy and the cap does
too, and also we usually want to tap off a little energy to use for the
application. This means we need to keep pumping more energy into
the tank circuit to make sure it keeps oscillating. This is usually done with
an amplifier of some sort. We can not simply make the gain equal to
unity however, because the oscillations would die down as the tank
circuit used up the energy and caused less and less feedback, so we
make the gain slightly higher than unity and that keeps providing enough
energy to feed the LC tank as well as the losses that are ever present.