Frequency stabilization of an LM566 VCO used in wide-band FM generation

The frequency stability problem, especially due to power supply variation, has been studied for an LM566 voltage controlled oscillator (VCO) used in the direct generation of wide-band FM. A simple scheme, based on premodulating the modulation component of the VCO control voltage, in accordance with the power supply variation, has been suggested for achieving frequency stability of the FM generator. The proposed stabilization circuit has been implemented and tested for satisfactory operation.