| 摘要 |
PURPOSE:To miniaturize a radio equipment by deciding an oscillating frequency via a varactor diode connected in parallel with an oscillation circuit and applying prescribed control to the capacitance by 1st and 2nd port circuits provided with similar diodes connected in parallel. CONSTITUTION:The varactor diode 6 having a capacitance C6 subjected to feedback control from a PLL is connected in parallel with the oscillator circuit comprising a coil 5 and capacitors 2-4 and an FM carrier whose frequency is stable is generated in a desired oscillating angular frequency omega at a broad band. Moreover, a series circuit comparing the 1st and 2nd port circuits 7, 8 provided with a similar varactor diode whose capacitance is C7(C8) controlled by a modulation signal Vm is connected in parallel with said circuit to apply FM modulation. Then as the frequency omega increases, the capacitance C7 is increased or the capacitance C8 is decreased, the deviation is decreased in the FM modulation sensitivity SFM based on equation has a small deviation even if the frequency is increased, stable and highly accurate FM modulation with broad band is applied by using one PLL to miniaturize the FM radio equipment, where K is a constant, (n) is a constant depending on the type of diode and Ls is an inductance of the coil 5 in the equation.
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