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.

12.5 An error-based controlled single-inductor 10-output DC-DC buck converter with high efficiency at light load using adaptive pulse modulation

Abstract: Reducing the number of large external components, especially inductors, is a very important issue for Power-Management ICs (PMICs). Single-Inductor Multiple-Output (SIMO) converters are excellent candidates to meet this requirement [1-3]. However, there are several issues with SIMO converters, such as cross regulation, instability and inefficiency at light load. Under normal load conditions, comparator-based controlled SIMO converters [1,2] show good cross regulation performance due to the fast response of the comparator. However, the switching loss remains constant and degrades light load efficiency due to the fixed switching frequency of output switches. The low-efficiency characteristic when any output is under light load condition is a critical issue that must be solved because a SIMO converter is very suitable for light load applications. In addition, the cross regulation issue appears again when any output is under no load because the output receives energy from the inductor every cycle despite the load condition. To solve these issues, a SIMO converter was previously reported to support Pulse Frequency Modulation (PFM) mode [3]. However, the mode change control method increases the complexity of the control loop, which makes it unsuitable for a multi-output SIMO converter. In this paper, an Error Based Controlled (EBC) SIMO converter is presented to resolve the problems raised above using load-dependent Adaptive Pulse Modulation (APM). A hybrid topology composed of a switching converter and a linear regulator is also presented to minimize the cross regulation issue. To highlight the advantages, a 10-output SIMO converter is designed.

Different PWM modulation techniques indexes performance evaluation

Abstract: Fully digital AC drives with pulse width modulated inverters are becoming an industrial standard. For PWM inverters several strategies are used. A complete view of the most common carrier based strategies, as sinusoidal PWM, third harmonic injected PWM, discontinuous or dead band PWM and space vector PWM is presented. The authors propose a method based on 'quality factors' to evaluate the different types of modulation. >

Fundamentals of a Pulsewidth Modulated Power Circuit

Abstract: This paper describes the practical design and operating principles of the pulsewidth modulated (PWM) inverter. The use of this power circuit in a variable voltage, variable frequency ac motor drive is emphasized. A comparison with the conventional adjustable voltage input inverter is made with respect to input-output characteristics as well as the effect of the unit on the input supply. This paper demonstrates the ability to design and produce a practical system using state of the arts components.

A monolithic step-down SC power converter with frequency-programmable subthreshold z-domain DPWM control for ultra-low power microsystems

Abstract: This paper presents a fully integrated switched-capacitor (SC) power converter for ultra-low power microsystems. The design features an efficient step-down charge pump and a frequency-programmable digital feedback controller. The controller is designed in the subthreshold region to reduce power dissipation significantly. It employs a programmable switching frequency digital pulse-width modulation (DPWM) to maintain high efficiency under various loading scenarios, without causing random noise spectrum as in pulse-frequency modulation (PFM). The monolithic implementation effectively suppresses switching noises and glitches introduced by parasitic components from traditional bonding, packaging and PCB wiring. The test prototype was designed and fabricated with a 0.35-mum digital CMOS N-well process. It supplies a variable power output from 0.8 to 1.5 V and from 400 muW to 7.5 mW precisely, with a variable switching frequency ranging from 200 KHz to 1 MHz. The converter achieves 66.7% efficiency with a controller power of only 147.5 muW.

Spectral aliasing effects of PWM signals with time-quantized switching instants

Abstract: This paper investigates the problem of the spectrum effects that appear in the power spectrum density (PSD) of a digitally implemented Pulse Width Modulated (PWM) signal. We recognize that as the digital implementation forces the switching instants to be time-quantized, an aliasing effect modifies the properties of the original PWM spectrum. Furthermore, we analyze, through analytical tools and numerical simulation, such effects for two typical cases: a sinusoidal modulating signal and Pulse Amplitude Modulated (PAM) carrying a maximum information modulating signal.