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.

Notes on the theory of modulation

Abstract: The transmission system of "frequency modulation" (transmission by variation of the frequency of the radiated wave) is mathematically analyzed, and the width of the band of frequencies occupied by this method of transmission at a given speed is compared with the width of the corresponding band for transmission by amplitude variation. It is proved that the frequency modulation system using a spacing or compensating wave is inferior to the amplitude variation system both as to the width of the frequency band occupied and as to distortion of signal waveform.

Frequency synthesizer systems and methods for three-point modulation with a DC response

Abstract: A frequency synthesizer includes a controlled oscillator which is responsive to a frequency control input signal, to generate an output frequency. A programmable frequency divider is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal. A phase comparator is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and to the divided signal, and thereby produce a first error signal. A sigma deltamodulator is responsive to a modulation input to produce the divided control input. A loop filter is responsive to the first error signal, to thereby produce the frequency control input signal. Ripple compensation signals and direct modulation signals may also be provided, to provide three-point modulator for a frequency synthesizer. Analog and digital embodiments may also be provided.

Proposal of Adaptive-Learning Neuron Circuits with Ferroelectric Analog-Memory Weights

Abstract: Novel adaptive-learning neuron circuits are proposed, in which a pulse frequency modulation (PFM) system is used and the interval of output pulses is continuously changed through the learning process. Key components of the circuits are adaptive-learning metal-insulator-semiconductor field-effect transistors (MISFETs) in which the gate insulator films are composed of a ferroelectric material and their polarity is gradually changed by applying input pulses to the gates. In the multiple-input neuron circuits, it is proposed that the adaptive-learning MISFETs be connected in parallel and the function corresponding to the excitatory and inhibitory synapses in a human brain be realized by applying positive and negative pulses to the gates of MISFETs. Finally, the layout of the synapse array between two neuron layers is discussed and the effectiveness of using a silicon-on-insulator (SOI) structure is demonstrated.

Space vector modulator for forced commutated cycloconverters

Abstract: A pulse-width modulation (PWM) control technique for forced commutated cycloconverters is presented. The technique is based on the space vector representation of the voltages in the complex plane. It is shown that with the allowable switching combinations, six output voltage space vectors with varying amplitudes can be obtained, in addition to the zero vector. The variation is compensated by adapting the standard modulation technique. The technique permits space vector synthesis of a three-phase, nonsymmetrical, nonsinusoidal output voltage, even under non-steady-state conditions, which is essential for the control of AC servo drives. A detailed explanation of the modulator principles and the switch control as well as simulation results for the time- and frequency domain analysis is given. The results are compared with the results obtained using the standard modulation technique. A possible microprocessor implementation of the modulator is also proposed. >

Direct modulation of semiconductor lasers

Abstract: Methods for direct modulation of semiconductor lasers are reviewed with the objective of indicating the advantages and limitations of each method. Techniques for producing amplitude, pulse, and frequency modulation of the optical wave are included. The modulation capabilities of present pulsed lasers are analyzed with special attention given to their operation at room temperature. In addition, several ways of producing analog position or width modulation of microwave-rate optical pulses are described, and the capabilities of optical frequency modulation by acoustic waves are reviewed. A new way of obtaining mode-locked optical pulses with a semiconductor laser is also suggested.