Showing papers on "Pulse-frequency modulation published in 2006"

Constant boost control of the Z-source inverter to minimize current ripple and voltage stress

Abstract: This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching frequency. The relationship of voltage gain to modulation index is analyzed in detail and verified by simulation and experiments.

Switching power converter employing pulse frequency modulation control

Abstract: A method for controlling a switching power converter provides an efficient algorithm for controlling the output voltage across loads that are relatively light with small transients. When the output voltage is at or below a predetermined first magnitude, a determination is made of the charge required for one or more pulses to increase the output voltage to a predetermined second magnitude which is greater than a target output voltage. Corrective action is taken to raise the output voltage to the second magnitude and the system takes no further corrective action until output voltage is determined to be at or below the first magnitude. The method is useful with synchronous or non-synchronous power converters of buck, boost, buck/boost or other topologies. The method further provides a simple means for determining the amount of charge removed from a battery.

All-digital DPWM/DPFM controller for low-power DC-DC converters

Abstract: A digital controller for dc-dc switching converters used in battery-powered handheld devices is introduced. The controller can operate in two modes and encompasses designs of a digital pulse-width modulator (DPWM) and an all-digital pulse-frequency modulator (DPFM). The DPWM has a high resolution and can operate at very-high constant switching frequency (tens of MHz). The DPFM features very-low power consumption, programmable on-time and control over switching frequency range. An experimental FPGA prototype and an application-specific IC that employ controller architecture are built around 3.3 V, 3W, 6 MHz buck power stage and successful operation of the digital controller in both modes is verified. The low power consumption has been also verified on a chip implemented in a standard CMOS 0.18/spl mu/m process.

Switch mode power supply control systems

Abstract: This invention generally relates to control systems for switch mode power supplies (SMPS), in particular digital control schemes. A switch mode power supply controller employing a combination of pulse frequency modulation and pulse width modulation to control a power switching device, the controller having: an input to receive an output voltage dependent feedback signal; an output for driving said power switching device; and a controller to provide a switching control signal to said output responsive to said feedback signal from said input, said switching control signal having a switching cycle including an ON portion for switching on said power switching device, and wherein said controller is configured to select one of a plurality of discrete pulse widths for said ON portion of said switching cycle using at least one stored pulse width, and to vary a duration of said switching cycle responsive to said feedback signal.

Wireless transmission apparatus, polar modulation transmission apparatus, and wireless communication apparatus

Abstract: A wireless transmission apparatus of multi-mode operation with superior power efficiency is provided. Switches ( 115 and 117 ) are switched over in such a manner that a modulation signal outputted from a wireless GSM/EDGE (UB) signal formation circuit ( 101 - 3 ) of a high-frequency signal processing circuit ( 101 ) is outputted to a high-frequency power amplifier ( 104 ) at the time of output of a GSM modulation signal, and is outputted to a high-frequency amplifier ( 105 ) at the time of output of an EDGE modulation signal. As a result, the EDGE modulation signal is power amplified using a high-frequency power amplifier ( 105 ) for an UMTS modulation signal use that is compatible with regards to the EDGE modulation signal and the maximum output power and presence or absence of envelope fluctuation. It is therefore possible to amplify the EDGE modulation scheme wireless signal with high efficiency.

Data transmitting apparatus and data receiving apparatus

Abstract: [PROBLEMS] To provide a data communication system that can perform a light modulation of brightness perceivable to human eyes and that can perform high quality communication using illuminating light. [MEANS FOR SOLVING PROBLEMS] A PWM modulating circuit (11) creates a PWM modulation signal in which the pulse width has been adjusted in accordance with a light amount control signal corresponding to a desired light amount. The PWM modulation signal is sent to a phase inverting circuit (12). For example, when a transport data signal is 0, the phase inverting circuit (12) outputs the PWM modulation signal as it is. When the transport data signal is 1, the phase inverting circuit (12) inverts the phase of the PWM modulation signal and then outputs the phase-inverted signal. In accordance with this phase-inverted signal, a light source driving circuit (13) drives a light source (14), such as an LED or an organic EL, thereby causing it to emit a light. In a data receiver (2), a photo-sensor (21) converts the light irradiated from the illuminating apparatus (1) to an electric signal, and a phase detecting circuit (22) detects the phase from the electric signal and outputs the received data signal.

10-Gb/s millimeter-wave signal generation using photodiode bias modulation

Abstract: We present a simple 120-GHz-band millimeter-wave (MMW) modulation method that uses the bias-voltage dependence of unitraveling-carrier-photodiode output power, which we call photodiode (PD) bias modulation. We investigated the dependence of the output-power-saturation mechanisms on the bias voltage. We used a lowpass filter in the bias circuit to increase the modulation bandwidth, and the 3-dB modulation bandwidth was over 7 GHz. We demonstrated the modulation of 120-GHz MMW signals at a data rate of 10 Gb/s using PD bias modulation.

Resonance DC/DC Converter and Control Method Thereof

Abstract: The present invention refers to a method for controlling a resonance DC/DC converter, which adjusts an output voltage by changing a turn-on frequency of input switch devices of a resonance circuit of the converter, and extends the range of the output voltage of the resonance circuit by adjusting the duty ratio of the switch devices based on the feedback signal of the load circuit. The present invention also provides the resonance DC/DC converter structure using the controlling method. The advantage of the present invention lies in the use of two modes of frequency modulation and frequency modulation plus pulse width modulation to control the resonance DC/DC converter; the use of the frequency modulation controlling mode when the operating frequency of the power supply is low, and introducing the frequency modulation plus pulse width modulation controlling mode when the operating frequency of the power supply is too high. As a result, the problem of the resonance converter, that is, the high operating frequency and the big loss of the circuit when the circuit operates at a light load and non-load, can be solved, and thus the regulation ability for the output voltage of the resonance circuit is enormously improved, and the output range of the voltage is effectively expanded.

Information processing apparatus and fan control method

Abstract: According to one embodiment, an information processing apparatus includes a main body, a fan which is provided in the main body and is driven by a pulse width modulation signal (PWM signal), and a fan control unit which varies a duty ratio of the pulse width modulation signal (PWM signal) and a frequency of the pulse width modulation signal (PWM signal) in accordance with a target rotational speed of the fan.

Pulse frequency modulation based CMOS image sensor for subretinal stimulation

Abstract: We have developed a CMOS image sensor based on pulse frequency modulation for subretinal implantation. The sensor chip forms part of the proposed intraocular retinal prosthesis system where data and power transmission are provided wirelessly from an extraocular unit. Image sensing and electrical stimulus are integrated onto the same chip. Image of sufficient resolution has been demonstrated using 16times16 pixels. Biphasic current stimulus pulses at above threshold levels of the human retina (500 muA) at varying frame rates (4 Hz to 8 kHz) have been achieved. The implant chip was fabricated using standard CMOS technology

Traffic preemption system communication method

Abstract: A remotely-controlled traffic preemption system and method includes an encoder circuit, an optical source, an optical detector, and a decoder circuit. The encoder circuit is adapted to generate a set of signal pulses. At least one bit of a data word is encoded as a function of amplitude modulation of a first subset of the set of signal pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of signal pulses. The optical source is adapted to transmit a set of light pulses having a respective light pulse for each signal pulse of the set of signal pulses. The optical detector is adapted to receive the set of light pulses. The decoder circuit is adapted to generate the data word from the set of light pulses received at the optical detector.

Optically coupled type isolation circuit

Abstract: In an optical coupled isolation circuit, a PWM encoder encodes a one-bit binary data signal supplied from a sigma-delta analog-digital converter in synchronization with a clock signal of a cycle T to produce a pulse width modulation signal. The pulse width modulation signal includes a narrower pulse having a width of 1/T and a wider pulse having a width of 3/T according to binary codes "0" and "1 ". The pulse width modulation signal is transmitted to a decoder as a recovered pulse width modulation signal through a light emitting device, a light detector and an optical recovery circuit. A decoder decodes the recovered pulse width modulation signal at timing of a half of the clock cycle from each rising edge of the recovered pulse width modulation signal. The rising edge is synchronized with the clock signal. Thus, the clock signal and the data signal can be transmitted in one channel.

Low-biased microwave-photonic link using optical frequency or phase modulation and fiber-Bragg-grating discriminator

Abstract: A linear microwave-photonic link is presented in which a fiber Bragg grating converts phase modulation into intensity modulation. DC-bias-related noise is reduced using a grating response that provides linear intensity modulation with low DC bias.

Pulse-width modulation for microcontroller servo control

Abstract: 27 0278-6648/06/$20.00 © 2006 IEEE ANIMATRONICS ARE USED in the movie industry to bring aliens, dinosaurs, and man-eating sharks to life. Many mechanical devices are used to impart realism to these puppets. Large motors and hydraulics are employed to control limbs, necks, and other areas requiring high torque. Small motors are used to create facial expressions, control eyes, and provide fluidity of movement to add life to these robots. A common motor used in animatronics is a servo motor. Instead of providing constant rotation, like most motors, servos are used for precise angular positioning but are often limited to only 180◦ of maximum rotation. Dozens of servos are used to control the facial expressions of a robotic puppet. Even a simple android might have five servos controlling just the eyes. The latex skin or muscles of an android’s face are connected to the servo’s shaft so that the servo can contort the face into different expressions. Servos are also common in devices such as radio-controlled cars to control steering, radio-controlled airplanes to control rudders, or even in the cruise control systems of cars. Servos are ideal for applications requiring absolute positioning of a motor shaft. Microcontrollers are an excellent and inexpensive device for controlling servos. In order to properly control a servo with a microcontroller, it is necessary to learn a few techniques, such as properly generating a control signal for a servo, which the rest of this article will cover. Servos may be purchased in a prepackaged form, or you can create your own servo with a few common components. Internally, a servo can be thought of as a direct current (dc) motor (which rotates an external motor shaft but provides no way to determine the amount of rotation) with a built-in controller. The control circuitry compares an angular position, determined by a control signal, to the current position of the motor shaft (as shown in Fig. 1). The motor shaft’s angular position is often determined by a potentiometer, which is rotated by the motor shaft. A potentiometer is a three-terminal resistor whose center connection has variable resistance, usually controlled by a slider or dial. The potentiometer acts as a variable voltage divider. The voltage from the center connection of the potentiometer represents the angular position the motor shaft is in. Other methods to determine angular position and rotation exist for bigger servos, but a potentiometer is the most common for small servos. The built-in controller generates an internal signal from the voltage controlled by the potentiometer, compares it to the control signal, and then provides power to the dc motor to rotate the shaft in the appropriate direction to match the two. Servos usually require a pulse-width modulated control signal.

Quadrature modulation circuits and systems supporting multiple modulation modes at gigabit data rates

Abstract: Quadrature modulation systems, circuits and methods are provided to support various modulation modes including ASK (amplitude shift key), FSK (frequency shift key) and PSK (phase shift key) modulation at high data rates (e.g., gigabit data rates). For example, a modulation circuit includes a mixer circuit including an integrated sign modulation control circuit and a plurality of mixer ports. The mixer ports include a first input port, a second input port, an output port and a sign modulation control port. The modulation circuit generates a modulated signal by operation of the mixer circuit multiplying a modulating signal applied to the first input port with a carrier signal applied to the second input port to generate a mixed signal output from the output port, and by operation of the integrated sign modulation control circuit controlling polarity switching of a signal at one of the mixer ports in response to a sign modulation control signal input to the sign modulation control port. The sign modulation control signal can be a digital data signal having binary data encoded into the modulated signal.

Transmission modulation apparatus, communication apparatus and mobile wireless apparatus

Abstract: Provided is a transmission modulation apparatus, using polar modulation of two-point modulation scheme, capable of completing a timing adjustment of a BB phase modulation signal and BB amplitude modulation signal in a short time. A phase modulation section ( 10 ) that performs two-point modulation with a PLL circuit is provided with a switch ( 17 ) to make the PLL circuit open loop, and when a first delay section ( 5 ) corrects the deviation in synchronization between the BB phase modulation signal and BB amplitude modulation signal, the switch ( 17 ) is turned off to make the PLL circuit open loop.

Multilevel Digital Pulse Interval Modulation Scheme for Optical Wireless Communications

Abstract: In this paper a new pulse time modulation technique known as Multilevel-Digital Pulse Interval Modulation (MDPIM) is introduced and its properties are presented. Expressions for the pulse train, bandwidth, transmission rate and capacity are given. The performance of MDPIM is compared with other pulse modulation techniques. Also system block diagram and signal simulation are presented.

Transmission apparatus, communication apparatus and mobile radio apparatus

Abstract: Transmission apparatus capable of reducing distortion of the vector modulation wave that is the transmission output to a sufficiently small level is provided. An amplifying section ( 105 ) generates a vector modulation wave based on an amplitude component modulation signal and a phase modulation wave. A synchronous demodulating section ( 107 ) detects the vector modulation wave, generates a synchronous demodulation signal, and sends this to a band filtering section ( 108 ). The band filtering section ( 108 ) extracts a signal of the frequency component of the distortion from a synchronous demodulation signal outputted by the synchronous demodulating section ( 107 ). A controlling section ( 109 ) then refers to the distortion component signal extracted by the band filtering section ( 108 ), controls a delay time adjusting section ( 103 ) in such a manner that the signal level of the distortion component becomes small, adjusts a delay time difference between the amplitude component modulation signal and the phase component modulation signal, and reduces distortion of the modulation wave.

Modulation methods based on a novel carrier-based PWM scheme for matrix converter operation under unbalanced input voltages

Abstract: In this paper, 1) a carrier-based modulation scheme for matrix converters, that is as simple as that in conventional PWM inverters for motors drives, is extended to unbalanced input voltages, and 2) three different modulation schemes are presented and verified by experiments.

Spread spectrum clock generation

Abstract: There is provided a method of modifying a first clock to generate a second clock with reduced electromagnetic interference (EMI). The method comprises receiving the first clock, generating an upslew modulation form during an upslew frequency transition, generating a downslew modulation form during a downslew frequency transition, modulating a frequency of the first clock over a period of time using the upslew modulation form and the downslew modulation form to generate the second clock, and wherein the upslew modulation form and the downslew modulation form are different. The upslew modulation form and the downslew modulation form are defined by upslew modulation values and downslew modulation values, respectively, and the method further comprises receiving the upslew modulation values and the downslew modulation values, and generating fractional upslew modulation values and fractional downslew modulation, respectively, for modulating the frequency of the first clock.

Boost DC/DC converter

Abstract: A boost DC/DC converter, including a mask circuit, a switched boost circuit, a pulse width modulation (PWM) circuit and an AND gate, is provided. The mask circuit is used to output a mask signal according to a load current. In the present invention, the system can selectively operate in the pulse width modulation mode, the pulse frequency modulation (PFM) mode or the mixed pulse mask mode according to the mask signal corresponding to the load current when the system is under light load, medium load or heavy load respectively, so as to achieve optimal system efficiency.

Variable edge modulation in a switching regulator

Abstract: In one embodiment, in a power converter system having a load, a method is provided for varying the type of modulation employed for a pulse width modulation (PWM) signal. The method includes the following: monitoring the load of the power converter system; using leading edge modulation for the PWM signal under light load condition; and using trailing edge modulation for the PWM signal under heavy load condition; thereby optimizing operation of the power converter system.

Analysis of pulse width modulation techniques for AC/DC line-side converters

Abstract: The paper presents the analysis of the modulation strategies for the AC/DC line-side converters. The application of the different modulation methods to the control system of the AC/DC converter has been presented. The operation of the AC/DC converter in different dynamic states strongly depends on the modulation method applied. The theoretical background of Hysteresis-Band Modulation, Carrier-Based Sinusoidal Modulation and Space-Vector Modulation has been presented. The issue of overmodulation has been discussed. Voltage Oriented Control of the AC/DC line-side converter has been chosen to examine the presented modulation methods. The influence of the discussed modulation methods on the line current distortion and the switching frequency has been examined. The simulation results of the presented techniques have been demonstrated and concluded.

Apparatus and method for communicating an input signal in polar representation

Abstract: A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal. In the amplitude modulation implementation (AM), the oscillating signal is not modulated, but rather causes the switch to gate a reference signal that is substantially equal to or proportional to the information signal. In the FM and PM implementations, the signal that is output from the switch is modulated substantially the same as the modulated oscillating signal. In the AM implementation, the signal that is output from the switch has an amplitude that is a function of the information signal. In both embodiments, the output of the switch is filtered, and the desired harmonic is output.

Performance Analysis of Random Pulse-Width Modulated Z-Source Inverter with Reduced Common Mode Switching

Abstract: This paper proposes and comparatively evaluates a number of different pulse-width modulation (PWM) schemes that can be used for Z-source inverter control to achieve buck-boost energy conversion with random and reduced common mode (RCM) switching. The presented schemes are developed systematically by firstly identifying an appropriate RCM PWM scheme. Unlike a traditional voltage-source inverter, Z-source inverter does not require dead-time protection, and therefore various RCM alternatives can be used with each giving rise to different capacitive ripple current, THD and WTHD. Analytical formulas for calculating these performance indexes are derived and presented in the paper. The performance of the modulation schemes is next refined by integrating an appropriate random PWM scheme developed from different random modulation concepts. These concepts include random switching frequency (RSF) PWM, pulse frequency modulation (PFM) and a newly proposed random shoot-through time (RST) PWM that can only be used with a Z-source inverter either as a standalone module or with RSF PWM to form a dual random modulation scheme. The developed PWM schemes are lastly tested in Matlab simulation and experimentally using a laboratory prototype with the captured results presented sequentially in the paper.

Amplifier, information communication apparatus and amplification method

Abstract: An amplifier includes a modulation coder receiving an original modulation signal and generating an amplitude signal and a phase signal, a voltage adjusting instrument which generates an amplitude modulation signal from the amplitude signal, a carrier generator generating a phase modulation signal from the phase signal, and an amplification device receiving the phase modulation signal and the amplitude modulation signal serving as a bias voltage and outputting a modulation signal obtained by restoring and amplifying the original modulation signal. The voltage adjusting instrument determines a DC offset voltage on the basis of a level control signal indicating the level of the amplitude modulation signal and generates the amplitude modulation signal to which the DC offset voltage is added.

Frequency modulation linearization system for a Fractional-N Offset PLL

Abstract: A linearization system is provided for a Fractional-N Offset Phase Locked Loop (FN-OPLL) in a frequency or phase modulation system. In general, the linearization system processes a modulation signal to provide a linearized modulation signal to a fractional-N divider in a reference path of the FN-OPLL such that a frequency or phase modulation component at the output of the FN-OPLL is substantially linear with respect to the modulation signal.

A New Approach to the Harmonic Analysis of SPWM Waves

Abstract: The Sinusoidal Pulse Width Modulation (SPWM) wave is very important for the design of frequency and voltage adjustable DC to AC inverters. Currently, SPWM waves are usually generated through the pulse width modulation (PWM) pins of a singer-chip microcomputer or digital signal processor (DSP). In order to achieve desired SPWM waves and know them better, it is essential to analyze their harmonic components. In this paper, we introduce a new approach to the harmonic analysis of SPWM waves based on Discrete Fourier Series (DFS) and the area equivalent principle. The developed method is convenient and the results of simulation and experiments are more accurate compared to conventional methods. The advantages of our approach are confirmed by the simulation and experimental results.