| 摘要 |
PURPOSE:To form a phase modulation circuit with a wide band whose modulation frequency ranges to 0 - several MHz by providing the 1st monostable multivibrator obtaining a phase difference and the 2nd monostable multivibrator deciding the duty ratio so as to provide the phase modulation with a wide range over 360 deg.. CONSTITUTION:A PLL10 generates an output signal Nf0 having a frequency being an integral number of multiple of a frequency of a reference input f0 and phase-locked and the output signal is used as a trigger to change the output pulse width of a monostable multivibrator (MM1)6 by using a modulation input. Then the trailing of the pulse triggers a monostable multivibrator (MM2)7 to make the output duty ratio constant. Thus, the output phase of the monostable multivibrator (MM2)6 being the final output is changed against the output phase of a VCO4 or the phase of the reference frequency input f0. The modulation is improved because of excellent frequency stability as well as wide variable range of pulse width of the monostable multivibrator through the adoption of the PLL.
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