Patent
Device for continuous phase modulation by frequency synthesizer with phase-locked loop
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TLDR
In this paper, a variable oscillator and a phase-locked loop with a frequency division circuit, a phase comparator, and a low-pass filter are used to reduce the modulation in the loop.Abstract:
Device for continuous phase modulation, produced from a frequency synthesizer including a variable oscillator and a phase-locked loop with, in series, a frequency division circuit, a phase comparator and a low-pass filter. In order to reduce modulation in the loop, the modulation is applied not only to the input of the synthesizer but also, in compensation, in the loop. In order to eliminate the modulation residue in the loop, a control signal for the oscillator is derived by a circuit which performs a correlation between the residue of the modulation and the output signal from a filter producing the same filtering effect as the loop, and which receives the modulation signal from the input of the synthesizer.read more
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References
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Patent
Center frequency calibration for DC coupled frequency modulation in a phase-locked loop
TL;DR: In this article, a phase-locked loop circuit is automatically calibrated to generate a feedback signal for cancelling DC offsets at the input of the coupling integrator with a digital-to-analog converter and resistor network driven by a digital counter.
Patent
Phase-locked loop frequency modulation circuit for input modulation signals having low-frequency content
TL;DR: In this paper, a phase-locked loop frequency modulation circuit that compensates for the inability of a phaselocked loop to pass low-frequency content of an input modulation signal, and that may be utilized with existing communication apparatus, such as a cellular telephone voice radio, for accurate data transmission without having to modify such apparatus, includes a compensation circuit (50) for processing an input modality signal (72) to provide a compensation signal (78) that is added to a loop filter output signal (70) by processing the input modulation signal to provide the same effect as adding the
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TL;DR: In this article, the anti-pulling loop mechanism was proposed to cancel the effects of frequency perturbations on the oscillator by repetitive signals well beyond the bandwidth of the phase-locked loop.