Topic
Pulse-frequency modulation
About: Pulse-frequency modulation is a research topic. Over the lifetime, 4151 publications have been published within this topic receiving 53039 citations. The topic is also known as: PFM.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, a study on linear frequency modulation (LFM) pulsed signal transmission by four-dimensional (4D) antenna arrays is presented, where the influence brought by the periodic time modulation is analyzed.
Abstract: This paper presents a study on linear frequency modulation (LFM) pulsed signal transmission by four-dimensional (4-D) antenna arrays. LFM pulse is used as the input of 4-D antenna arrays and the influence brought by the periodic time modulation is analyzed. The relationship among pulse duration, chirp rate, sample frequency, time-modulation frequency, and propagation direction is analyzed and the restrictions to these parameters are highlighted. The transmitting and receiving structures are introduced and relevant signal processing steps are described. Numerical examples with several different time schemes, including the pulse shifting (PS) scheme and binary phase center motion (BPCM) scheme, are presented to demonstrate the effectiveness of the LFM signal transmission by 4-D arrays. Simulation results validate that original chirp signal can be correctly recovered and low sidelobe power patterns can be simultaneously achieved by 4-D antenna arrays, as long as the proposed limitations are satisfied.
25 citations
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28 Sep 1999
TL;DR: In this paper, a phase-locked loop applied as a phase modulator using an external analog control signal was proposed, whereby a single-ended pulse-width modulated digital signal may be derived from the phase detector output, and two phase modulated square-wave digital signals may be obtained from a reference oscillator and the feedback voltage controlled oscillator.
Abstract: A phase-locked loop applied as a phase modulator using an external analog control signal whereby a single-ended pulse-width modulated digital signal may be derived from the phase detector output, and two phase modulated square-wave digital signals may be derived from a reference oscillator and the feedback voltage controlled oscillator. The pulse width modulation and/or phase modulation in power applications can be achieved with far greater speed, precision, simplicity and economy than by existing techniques.
25 citations
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03 Oct 2007
TL;DR: In this article, a PWM/PFM control circuit has a differential time generating means for forming a differential-time signal representing the difference between the pulse width of PWM and PFM control signals, and the oscillation frequency of a reference signal serving as a reference for forming the PWM control signal is controlled based on the differential time signal.
Abstract: A PWM/PFM control circuit has a differential time generating means for forming a differential time signal representing a differential time corresponding to a difference between the pulse width of a PWM control signal and the pulse width of a PFM control signal on condition that the pulse width of the PWM control signal is smaller than the pulse width of the PFM control signal, and the oscillation frequency of a reference signal serving as a reference for forming the PWM control signal is controlled based on the differential time signal to a low value in accordance with the differential time.
25 citations
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TL;DR: In this paper, a novel pulse frequency modulation step-up dc-dc converter with maximum power conversion of 9191% and steady-state accuracy of 033% is presented, which uses a dynamic sensing current controller and a load current detector that accurately generates different energy according to various load conditions.
Abstract: A novel pulse frequency modulation step-up dc-dc converter with maximum power conversion of 9191% and steady-state accuracy of 033% is presented in this letter The high efficiency and exact output are achieved by a dynamic stored energy technique that enhances utility rate of energy with less power consumption This technique uses a dynamic sensing current controller and a load current detector that accurately generates different energy according to various load conditions The boost converter has been designed and fabricated with a standard TSMC 33/5 V 035- mum 2P4M CMOS technology Experimental results show that the output up-ripple voltage variation was 25 mV (61-86 mV), whereas its fixed energy counterpart was 394 mV (86-48 mV) The proposed boost converter has 16% higher power conversion efficiency than the conventional fixed energy technique at 1 mA load current
25 citations
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12 Oct 2003
TL;DR: In this paper, a low-power bipolar transistor is used to achieve low crest factor correction using a modified valley-fill filter to meet IEC61000-3-2 requirements.
Abstract: This paper presents an alternative to achieve fluorescent lamp current low crest factor, using the valley-fill filter as a passive power-factor-correction method. Pulse frequency modulation is used to reduce lamp current high crest factor. Self-oscillating electronic ballast is employed in order to avoid complex circuitry. The partial smoothing valley-fill DC-link bus voltage is used to control the switching frequency. Crest factor correction is achieved through a low power bipolar transistor, which connects a low power passive circuit parallel within the self-oscillating gate-driver circuit. The switching frequency changes in order to keep the lamp current crest factor lower than 1.7 and a modified valley-fill filter is used to meet IEC61000-3-2 requirements. Simulations and experimental results are presented to demonstrate the simplicity, and feasibility of the proposed system.
25 citations