Frequency modulated oscillator for radio links - has linear range increased by connecting RLC circuit in parallel with resonant circuit

摘要

The frequency modulated oscillator, for radio link's broadhand FM modulator, has the linear part of its characteristics increased so that it is suitable for direct modulation in a broadhand radio link with eg 2700 voice channels. (The oscillator oscillates at the link's IF frequency). This is achieved by connecting a series RLC resonant circuit (Cs, Ls, Rs) in parallel with the oscillator LC resonant circuit (VD, Ck, Lk). The series resonant circuit shifts the fall-off in linearity near the upper frequency limit to a higher frequency. The linearity may also be extended down to lower frequencies by increasing the reactance of the oscillator's LC resonant circuit.