Patent
Frequency modulator, frequency modulating method, and wireless circuit
Hisashi Adachi,Makoto Sakakura +1 more
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TLDR
In this paper, a phase-locked loop (PLL) was proposed to provide a frequency modulator that can use a reference signal source having no frequency modulation function, and perform modulation over a wide range of frequencies based on a digital modulation signal.Abstract:
A voltage controlled oscillator 1, a variable frequency divider 2, a phase comparator 3, and a loop filter 4 form a Phase Locked Loop (PLL). A sigma-delta modulator 5 sigma-delta modulates data obtained by adding a fractional part M2 of the frequency division factor data with modulation data X by using an output signal of the variable frequency divider 2 as a clock. An output signal of the sigma-delta modulator 5 is added to an integral part M1 of the frequency division factor data, and the resultant data becomes effective frequency division factor data 13 of the variable frequency divider 2. An output signal of the sigma-delta modulator 5 also becomes control data 14 after passing through a D/A converter 6, a low-pass filter 7, and an amplitude adjustment circuit 8. The control data 14 is inputted into a frequency modulation terminal of the voltage controlled oscillator 1. Therefore, it is possible to provide a frequency modulator that can use a reference signal source having no frequency modulation function, and perform modulation over a wide range of frequencies based on a digital modulation signal.read more
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Patent
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References
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Patent
Direct digital synthesis of precise, stable angle modulated RF signal
Earl W. McCune,Wendell B. Sander +1 more
TL;DR: In this paper, an adaptive gain amplifier (411) is used to inject a modulation signal into the PLL at a point past a loop filter (403), and a phase demodulator (419) recovers from the output of PLL phase information which is compared in a comparator (417) to the phase information of the modulation signal.
Patent
Two-port synthesizer modulation system employing an improved reference phase modulator
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Patent
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Frequency synthesizer apparatus equipped with fraction part control circuit, communication apparatus, frequency modulator apparatus, and frequency modulating method
TL;DR: In this article, a fraction part control circuit of a frequency synthesizer apparatus including a PLL circuit is of a plural-n-th-order delta-sigma modulator circuit for controlling the fraction part of a number of frequency division to a variable frequency divider of the PLL.
Patent
Digital phase modulation of frequency synthesizer using modulated fractional division
TL;DR: In this paper, a phase-locked loop frequency synthesizer system is provided using fractional frequency division and a fractional control number for phase modulating an output of the synthesizer using an incoming information signal.