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.

Frequency Modulation and the Effects of a Periodic Capacity Variation in a Nondissipative Oscillatory Circuit

Abstract: Certain fundamental characteristics of the theory of frequency modulation for arbitrarily large degrees of modulation and unrestricted modulation frequencies are developed from the differential equation for a dissipationless circuit with fixed inductance and variable capacitance. The several modes of modulating the frequency are discussed and classified; it is shown that they give the same results only when the amount of modulation is very small. The case of "inverse capacity modulation" is then treated in detail. This treatment discloses the possibility of unstable oscillations occurring with certain values of the parameters; the nature and physical significance of these unstable oscillations are determined, and it is explained why they are not ordinarily observable in radio-frequency modulation or in the warble tone generator. The frequency spectrum of the stable oscillations is found, and a means of calculating the amplitude given. For certain adjustments of the circuit the oscillations may be represented by a true Fourier series, while in general this is not the case. Frequency modulation in radiotelephony, the warble tone, and the special case where the natural period of the unmodulated circuit and the frequency of modulation are of comparable magnitude, represent successively more complicated cases of the same general phenomena; the latter is of special interest. The nature of the phenomena accompanying other than a sinusoidal inverse capacity variation is mentioned.

High-Efficiency LLC Resonant Converter With Reconfigurable Voltage Multiplying Rectifier for Wide Output Voltage Applications

Abstract: This article presents a reconfigurable voltage multiplying rectifier (RVMR) to improve the performance of an LLC resonant converter for wide output voltage applications. The RVMR can operate as voltage-doubler mode or voltage-quadrupler mode according to the primary switching strategy. Two operation modes split a wide output voltage range into two narrow ranges. Therefore, the RVMR enables the LLC resonant tank to be designed in a narrow output voltage range, which results in a narrow switching frequency range, high efficiency, and high power density. A smooth mode transition can be achieved by adopting a phase-shift control to general pulse frequency modulation control without any additional switch. The proposed RVMR LLC converter can improve its efficiency by 2.9% and reduce component volume by 26% compared to the conventional full-bridge LLC resonant converter. A 750-W prototype with 400 V input, 100–300 V output voltage, and 2.5 A max output current has been built and tested to verify the effectiveness of the proposed converter.

System and method for transmitting analog signals with a modulating retroreflector and hybrid amplitude and frequency modulation

Abstract: A system and method for encoding an analog input signal for optical transmission, including driving a voltage controlled oscillator with an analog input signal to produce a frequency modulated electrical signal having a frequency proportional to the amplitude of the input signal, and applying the frequency modulated electrical signal to a multiple quantum well modulating retroreflector. The retroreflector receives optical energy from a laser source and modulates the optical energy with the frequency modulated signal to produce an output optical signal.

Small-signal frequency responses for Si micro-ring modulators

Abstract: We present a new small-signal model for the modulation frequency response of a Si micro-ring modulator. The model is based on the coupled-mode theory and has the well-known second-order system characteristics. The accuracy of the model is confirmed with measured Si MRM small-signal frequency response.

On system identification using pulse-frequency modulated signals

Abstract: i ON SYSTEM IDENTIFICATION USING PULSE-FREQUENCY MODULATED SIGNALS Nonperiodic time quantization has proved very useful for the improvement of measurement and control systems. Very often nonperiodic time quantization is connected with pulse frequency modulation (PFM). In the present report some aspects of continuous system identification using PFM signals have been studied. Two possibilities for application of PFM signals in system identification are considered. In accordance with these possibilities either the system is excited by PFM signals or the system output is observed with the help of a pulse-frequency converter. For both these cases effective computational schemes for estimation of the transfer function and the weighting function have been obtained. For the case of the weighting function estimate, the relationship with previously obtained estimates has been established. The utility of the suggested estimates is illustrated by computer simulation. For this purpose, several programs are given in the appendix.