Re: If I dont attach Capacitor Bank with my LCVCO circuit, what is the disadvantage?
Capacitor banks are used to calibrate the VCO while the system is powered on.Because every die has some variations from nominal value of semiconductor process.In order to compensate these variations and to standardize the products, a calibration routine runs at the beginning of start-up.Also frequency drift occurs by temperature and aging , capacitor banks are used to regularize these drifts.
So, using spare circuits is a very well habit to maintain the same performance in any case of operation.
300MHz/V seems to me too high for a 2.45GHz VCO.Phase Noise will be so bad..But I don't know your required specifications.