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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
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Journal ArticleDOI
TL;DR: In this paper, the effect of gain saturation on the exact shape of the gain waveform is allowed for in a completely selfconsistent fashion, and the results of these studies showed good agreement with the predictions of the model presented here, in contrast with the prediction of the existing models.
Abstract: Existing frequency domain models for the active mode locking of diode lasers are appropriate for antireflection- (AR-) coated devices This paper presents the first frequency domain model for non-AR-coated devices The use of uncoated devices permits the independent measurement of all of the important laser parameters required for the model, so that no adjustable parameters are needed An additional novel feature of this model is that the effect of gain saturation on the exact shape of the gain waveform is allowed for in a completely self-consistent fashion Experimental studies were carried out on uncoated undegraded commerical laser diodes Threshold reductions of 25-30 percent were achieved for external cavity operation The mode-locking studies reported in this paper were carried out above the external threshold current, with a sinusoidal modulation near 1 GHz at a modulation index of 4 percent The results of these studies showed good agreement with the predictions of the model presented here, in contrast with the predictions of the existing models Specifically, the modulation frequency corresponding to the shortest most intense mode-locked pulses was found to occur at a fraction of 1 percent below the frequency matched to the external cavity roundtrip time As well, the predicted effects of gain saturation were observed in the detailed structure of the mode-locked pulses, and in their detuning characteristics

27 citations

Journal ArticleDOI
TL;DR: In this article, the spectrum of the output differential-mode voltage in a SPWM inverter with periodic CFM is analyzed theoretically, through changing the maximum frequency deviation, periodic signal's frequency and waveform of CFM, the suppression effects of interference peaks are discussed.
Abstract: The electromagnetic interference (EMI) of the inverter output, which is controlled through a sinusoidal pulse width modulation method, is mainly generated at the carrier frequency and its harmonics. The peaks of the interference can be reduced effectively by using carrier-frequency modulation (CFM). The spectrum of the output differential-mode voltage in a SPWM inverter with periodic CFM is analyzed theoretically in this paper. Through changing the maximum frequency deviation, periodic signal's frequency and waveform of CFM, the suppression effects of interference peaks are discussed. A new scheme, in which the carrier frequency is modulated twice, is presented. In this scheme, the frequencies and waveforms of periodic signals are optimized and selected under the condition of the same maximum frequency deviation, and the synthetic modulation signal which has the best suppression effect of the maximum interference peak is obtained. The feasibility and validity of the scheme are proved by simulation and experiment results in a single-phase inverter.

27 citations

Patent
09 Mar 2005
TL;DR: In this paper, a pre-stage side of a high-frequency power amplifier changes an amplitude of the high frequency phase modulation signal according to a base band amplitude modulation signal and a gain control signal.
Abstract: A transmission device having a preferable power efficiency and a wide control range of transmission output power. A pre-stage side of a high-frequency power amplifier changes an amplitude of a high-frequency phase modulation signal according to a base band amplitude modulation signal and a gain control signal. A variable gain amplifier changes the amplitude of the high-frequency phase modulation signal according to the base band amplitude modulation signal and the gain control signal, so that the base band amplitude modulation signal is supplied to an amplifier via a linear-log converter.

27 citations

Proceedings ArticleDOI
Wei Liu1, Binbin Wang1, Wenxi Yao1, Zhengyu Lu1, Xiaoyi Xu 
01 Sep 2016
TL;DR: In this article, a generalized phase shift modulation (PSM) LLC model is presented to provide accurate prediction on resonant voltage and current behavior, dc gain and all the other steady-state information.
Abstract: In many applications, phase shift modulation (PSM) has been proven to be a promising supplement of pulse frequency modulation (PFM) in LLC resonant converter. However, steady-state analysis of PSM LLC converter is not thoroughly studied yet. This paper presents a generalized PSM LLC model which can provide accurate prediction on resonant voltage and current behavior, dc gain and all the other steady-state information. Then, operation modes, mode boundaries and distribution are discussed with three cases according to the relationship between switching frequency and resonant frequency. Meanwhile, dc voltage gain and zero-voltage switching characteristics of each operation mode are briefly analyzed. Simulation results verify the accuracy of proposed analysis.

27 citations

Patent
14 Dec 1995
TL;DR: In this article, a method for investigating a scattering medium, especially a biological matrix, with intensity-modulated light, is proposed, in which a high-frequency modulation signal is generated by a frequency generator (18), the intensity of a light emitter (10) is modulated with a modulation signal and the light from the emitter is radiated into the medium, the modulation signal includes frequency chirps during which the modulation frequency is tuned from an initial frequency to a final frequency.
Abstract: The invention concerns a method for investigating a scattering medium, especially a biological matrix, with intensity-modulated light. In order, in such a frequency-domain measuring procedure, to reduce the expenditure on electronics without restricting accuracy of measurement, a method is proposed, in which, in order to investigate a scattering medium, especially a biological matrix, with intensity-modulated light, a high-frequency modulation signal is generated by a frequency generator (18), the intensity of a light emitter (10) is modulated with a modulation signal and the light from the light emitter (10) is radiated into the medium, the modulation signal includes frequency chirps during which the modulation frequency is tuned from an initial frequency to a final frequency, the modulation signal is delivered from the frequency generator (18) via at least two different signal paths (23A, 24) to a signal mixer (31), so that during a frequency chirp the input signals of the signal mixer (31) differ by a differential frequency whose magnitude is a function of the difference between the signal transit times over the at least two signal paths (23A, 24) and of the rate of change of the modulation frequency, wherein at least one of the signal paths includes a light path section (20A) passing through the medium as a measurement signal path (23A), and the output signal of the signal mixer (31) is further processed to produce information relating to the scattering medium (FIG. 2).

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202228
202143
202055
201950
201860