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.

Systems and methods for flyback power converters with switching frequency and peak current adjustments

Abstract: System and method for regulating a power converter. The system includes a comparator configured to receive a first signal and a second signal and generate a comparison signal based on at least information associated with the first signal and the second signal. The first signal is associated with at least an output current of a power converter. Additionally, the system includes a pulse-width-modulation generator configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, and a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter. The modulation signal is associated with a modulation frequency corresponding to a modulation period.

A comparison of CAP/QAM architectures

Abstract: Recently CAP modulation (Carrierless Amplitude and Phase modulation) has been of wide interest to industry because of its simplicity, bandwidth efficiency and zero dc component. This paper compares CAP versus QAM modulation and highlights some practical implementation issues. In addition, three different CAP-like architectures are compared according to A/D sampling-rates, A/D resolutions and jitter requirements.

Digital pulse-frequency modulation controller for switch-mode power supplies with frequency targeting and ultrasonic modes

Abstract: A digital pulse controller uses digital logic to send pulses to a high side and low side switches of a switch-mode power supply converter. The digital logic uses a pulse frequency mode which includes a frequency targeting mode and an ultrasonic mode. The frequency targeting mode dynamically adjusts the size of the pulses in order to achieve a switching frequency within a desired band. The ultrasonic mode is switched into when the frequency of the pulses are at or below a threshold and the time of the pulses reaches a minimum threshold.

A Method of Describing the Detectivity of Photoconductive Cells

Abstract: A simple method is proposed for describing the detectivity of photoconductive cells.First it is pointed out that at signal modulation frequencies well below the frequency that corresponds to the time constant of the cell, the responsivity of the cell is independent of the frequency. For the same range of signal modulation frequencies, the noise power (mean‐square noise voltage) per unit frequency bandwidth is inversely proportional to the frequency. It is a very general property of radiation detectors obeying Lambert's law that the detectivity varies inversely as the square root of the sensitive area.As a result of the facts just stated, one is led to the conclusion that if one multiplies the measured detectivity by the square root of the cell's sensitive area and by the square root of the band width of the noise, and if one divides by the square root of the frequency of the test signal, one obtains a result that is independent of the test band width and test frequency and is independent also of the sensi...

Pulse width modulation based signal format for visible light communications

Abstract: A pulse-width modulation (PWM) based modulation format is proposed for visible light communication (VLC) system using illumination light-emitting diodes (LEDs). A pulse-position modulation (PPM) data signal is employed over PWM dimming (brightness) control signal. The PPM data pulses are recovered from the received optical signal over a distance of 20 cm.