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.

Pulse width modulation carrier frequency technique

Abstract: A PWM method and circuit. A temporary PWM signal is generated at a first frequency. The temporary PWM signal includes analog duty cycle information adapted for the first frequency. At least a portion of the analog duty cycle information is converted to digital duty cycle information adapted for a second frequency. A final PWM signal having a carrier frequency of the second frequency is generated from the digital duty cycle information.

Phase modulation method for spread spectrum clock generator

Abstract: Spread spectrum clock generation (SSCG) using phase modulation. A first clock signal having a first frequency spectrum may be modulated using phase modulation to produce a second clock signal. The phase modulation may include providing a phase modulation profile corresponding to the integrated frequency modulation profile, to adjust a scaling factor used in obtaining the second clock signal. The phase modulation profile may be provided in the form of a pulse or pulses, which may be injected through pulse density modulation or pulse width modulation at the output of a phase frequency detector comprised in a phase locked loop circuit used in generating the second clock signal. This modified phase modulation technique removes the down spread limitation present in traditional PM implementations, and also provides better jitter performance and lower cost than traditional PM implementations.

Digital-to-analog conversion apparatus and method

Abstract: An indirect digital-to-analog conversion apparatus and method which combines the advantages of pulse rate modulation with pulse width or pulse duration modulation. Pulse duration modulation is used on the least significant bits; while pulse rate modulation is used on the more significant bits up to the most significant bit. In this manner, the advantages of both systems are combined resulting in a system in which conversion time is minimized while the ripple content in the analog output is also minimized.

RF modulation using a pulsed DC power supply

Abstract: Circuits for modulating an RF input signal applied to an RF high power amplifier to produce a modulated RF output signal. The present invention employs a VHF power supply or converter with a modulation control circuit that enables the power supply to be pulsed at frequencies commensurate with a radar in which it is employed, for example. Modulation of the high power amplifier is accomplished by applying a pulsed voltage output signal to a DC bias input of the high power amplifier. More particularly, the modulation control circuit receives a logic control signal, generates a pulse control signal in response thereto, and modulates a DC input signal processed by the converter. The VHF converter receives and modulates the DC input signal in response to the pulse control signal to cause the pulsed voltage output signal from the converter to pulse at a rate and duty cycle determined by the logic control signal. The output signal modulates the RF input signal amplified by the RF high power amplifier. The modulation control circuit comprises a digital input buffer for receiving the logic control signal, a driver circuit for generating the pulse control signal, and a modulation switch coupled to the converter for modulating the DC input signal in response to the logic control signal. This causes the output of the converter to pulse at a rate and duty cycle determined by the logic control signal. The converter may comprise a common emitter converter or a common base converter. The VHF converter comprises input and output wave shaping networks, the common base or common emitter inverters, an impedance matching network, and a rectifier/filter. The rectifier/filter is adapted to convert a sinusoidal signal produced by the inverter into the output signal that has a desired DC voltage for application to the high power amplifier.

A New Pulse Modulator for Accurate DC Amplification with Linear or Nonlinear Devices

Abstract: A new pulse-modulation technique and modulator circuit has been developed, offering several advantages over conventional methods. The technique and circuit are applicable in a broad range of control system and data transmission problems. Use of this method is appropriately considered in any application where dc or low-frequency information is to be amplified or transduced. In addition to both an intrinsically high degree of accuracy and the numerous potential advantages of sampled-data and digital techniques provided by use of this modulator, the modulator offers a solution to the bandwidth problems encountered in conventional pulse modulation methods. Pulse width modulation and pulse frequency modulation both require unrealizable infinite device bandwidth in order to obtain full control of the pulse train duty ratio between zero and unity. The modulator described in this article requires only a finite device bandwidth to obtain full control. The logical development of the modulator principles, based upon the requirements of limited bandwidth and good accuracy, are presented in this article. The mechanization of the modulator circuit in transistorized form is given, with the most accurate configuration discussed at length. Test results of the circuit are summarized. Application of the modulator is discussed, including both theory related to the application, such as modulator dynamic response characteristics and pulse demodulation, and specific applications in space vehicle autopilots, dc amplifiers and servo systems.