174 results about "Pulse-density modulation" patented technology

The present invention relates in one aspect to a class D audio amplifier with improved output driver topology supporting multi-level output signals such as 3-level, 4-level or 5-level pulse width or pulse density modulated output signals for application to a loudspeaker load. The present class D audio amplifiers are particularly well-suited for high-volume consumer audio applications and solutions.

An audio device (200) includes a first and second ICs (210) and (250) and a substrate (205). The first IC includes a sigma-delta, A / D converter (218) operable to convert an analog signal (234) into a pulse density modulated signal (236). A pulse density width modulator encoder (222) is operable to encode the PDM signal into a PDWM signal (244). The PDWM has short and long pulse widths defining first and second bit levels. The leading edges of each pulse bounds each pulse period. The second IC (250) includes a means (254) to receive the PDWM signal, an edge detector (304) operable to detect the leading pulse edges of the PDWM signal, a time-averaging circuit (308) operable to calculate each pulse period from the leading pulse edges and to generate a sample pulse (120) at near the midpoint of each pulse period, and a latch (312) operable to sample and hold the PDWM signal at the sample pulse to decode a PDM signal (278). The substrate is operable to support the first and second ICs and to conduct the PDWM signal between the first and second ICs.

A LED driver and controller system utilizes switches to parallel connect to respective sets of one or more LEDs and a current source to provide efficient control of the LEDs. In at least one embodiment, the LEDs are connected in series. An LED controller of the LED driver and controller system 200 controls conductivity of the switches. In at least one embodiment, the LED controller provides control signals to one or more LED drivers. The LED drivers receive the control signals and, in response to the control signals, control the conductivity of each switch. In at least one embodiment, the conductivity of the each switch is controlled using a duty cycle modulated control signal. In at least one embodiment, the duty cycle modulated control signal is a pulse width modulated control signal. In another embodiment, the duty cycle modulated control signal is a pulse density modulated control signal.

The invention relates to a dual-microphone-based speech enhancement device. The device comprises a digital microphone array module, a first pulse density modulation decoder module, a directivity formation module, a second pulse density modulation decoder module, a speech enhancement processing module and an output module, wherein the digital microphone array module is used for receiving a time domain noisy speech digital signal; the first pulse density modulation decoder module is used for performing frame separation, down-sampling and filtering on the time domain noisy speech digital signal to form an initial down-sampling rate digital signal; the directivity formation module is used for performing directive formation on the initial down-sampling rate digital signal to form an initially noise-reduced directive output signal; the second pulse density modulation decoder module is used for performing the frame separation, the down-sampling, the filtering and accentuation on the initially noise-reduced directive output signal to form a second down-sampling rate digital signal; the speech enhancement processing module is used for performing speech enhancement processing on the second down-sampling rate digital signal; and the output module is used for outputting a background noise-removed speech signal. The invention also provides a dual-microphone speech enhancement device-based speech enhancement method. The device and the method have a good denoising effect.

A digital audio-signal output circuit is provided, which is capable of outputting an audio signal without generating pop noise. In suppressing pop noise, the audio signal output circuit requires no analog circuit nor mute control signal for external peripheral devices. Upon receipt of a digital input audio signal having an AC component superposed on a reference voltage VREF, the circuit selects one of a pulse-density-modulated audio signal derived from the input audio signal and a transition signal that smoothly varies between zero volt and the reference voltage, and provides the selected signal to speakers.

A high performance method and apparatus for testing a closed loop transducer is disclosed. A test bitstream signal is combined with a SIGMA DELTA feedback bitstream of the transducer to produce a combined bitstream which is converted to a physical feedback to the sensor of the transducer. The SIGMA DELTA bitstream output of the transducer is recorded for later analysis so as to test characteristics of the transducer. The test bitstream signal is preferably an oversampled, pulse density modulated signal. A testing arrangement is provided which is based upon the storage of short-length test patterns which are repetitively accessed to form a continuous test pattern. The test bitstream provided by the method of the invention produces very low noise and low distortion test signals where a repetitive test pattern is equivalent in length to one period of the test signal.

Dithering for the output of a digital pulse width modulator is provided by a pulse-density modulator formed from an adder incrementing a pulse-density count and generating a carry signal latched to a plus-one generator, which in turn adds a phase-division period to each of one or more selected pulses within a predetermined series of pulses from the digital pulse width modulator. Selected pulses are advanced by triggering a leading edge of the pulse at a time one phase-division period before the system clock edge, allowing trailing edges to be extended and providing minimal latency delay.

The present disclosure refers to a digital microphone device providing a single-bit Pulse Density Modulation PDM output signal. The digital microphone comprises a microphone, arranged to convert an acoustic input signal into an analog electrical signal, and a preamplifier, having a variable gain, arranged to receive the analog electrical signal and to provide an amplified analog electrical signal, depending on the variable gain. The variable gain depends on a gain control signal. The digital microphone further comprises an Analog-to-Digital Converter block, arranged to receive the amplified analog electrical signal and to convert it into a respective digital signal; and a compensation block, arranged to receive the digital signal and to perform a digital operation on such digital signal, on the basis of a compensation signal, to generate a compensated signal. Furthermore, the digital microphone comprises an Automatic Gain Controller block 25, arranged to detect the digital signal and to generate said gain control signal, on the basis of the detected digital signal. The Automatic Gain Controller block is further arranged to generate the compensation signal, on the basis of the control signal, and to provide the compensation signal to the compensation block, to compensate a variation of the digital signal resulting from the variable gain of the preamplifier. Finally, the digital microphone device comprises a conversion block, arranged to receive the compensated signal and to convert it into the single-bit PDM output signal.

Present invention discloses pulse number modulation based atmospheric pressure glow discharge control method and circuit. Control method adopts pulse density modulation to generate alternate presented square wave pulsing signal to control inversion circuit switch tube on / off in glow discharge main circuit, each working period containing fixed quantitative square wave pulse, through keeping working period unchanged and changing working period square wave pulse number to control inversion circuit feeding energy time to load, realizing atmospheric pressure glow discharge load fixed frequently constant voltage control. The present invention can realize frequency follow-up control and linear power regulation to atmospheric pressure glow discharge type nonlinear variational capacitive loading.

The endoscope beam source apparatus includes a beam source for emitting a radiation beam to be supplied to the endoscope, and a beam source control unit for controlling the emission beam intensity of the beam source according to a beam quantity specified value input therein. The beam source control unit specifies the emission beam intensity corresponding to the beam quantity specified value based on at least three of control amounts. The control amounts include a control amount corresponding to pulse number modulation (PNM) control for changing lighting time of the beam source, a control amount corresponding to pulse width modulation (PWM) control for changing a plus width which indicates the lighting or lighting-out time within a control cycle, a control amount corresponding to pulse amplitude modulation (PAM) control for changing the lighting intensity, and a control amount corresponding to pulse density modulation (PDM) control for changing a lighting interval.

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.

The present invention relates to a method and system for providing an analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. A band-limited digital noise signal indicative of a Gaussian noise signal having a predetermined Gaussian probability distribution function is ΣΔ modulated generating a pulse-density modulated 1-bit sequence representing a Gaussian noise signal having a predetermined probability distribution function, bandwidth and center frequency. Using an analog low-pass filter the pulse-density modulated 1-bit sequence is then converted into a respective analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. The method and system are successfully employed in numerous applications such as in histogram testing and probabilistic digitization.

A circuit and a method for performing pulse width modulation are provided. A pulse density modulator (PDM) is applied to receive the least N bits of the input data and to generate a pulse density modulation signal. The number of pulse of the pulse density modulation signal in 2{circumflex over ( )}N frames correspond to a value of the least N bits of the input data. An adder is applied to generate a PWM data by adding a value of the most M bits of the input data to a value of the pulse density modulation signal generated by the PDM. A pulse width modulator is applied to generate a PWM signal dithering in 2{circumflex over ( )}N frames according to the PWM data generated by the adder, so as to improve the audio quality of pulse width modulation and the Electro-Magnetic Interference (EMI) phenomenon.

A method for modified pulsed control of an electromechanical actuator in accordance with the invention comprising the steps of a) setting a common time length for all of the pulses in a pulse train, and b) varying (modulating) the number of such pulses per unit time (repetition rate) by varying the length of time between pulses in the train. Such control is defined herein as pulse-density modulation, or PDM. Especially in applications having a relatively low percent duty cycle if controlled by the prior art Pulse Width Modulation (PWM), PDM control results in more accurate control of an actuator, with higher resolution. The method is especially useful in controlling flow of a fluid, through a valve, such as a fuel injector, and especially at relatively low flow rates at high supply pressures P1 in the fluid supply.

A method eliminates spectral lines in a time hopping ultra wide bandwidth signal. First, a train of pulses is generated from input symbols. The pulses are then modulated in time according to symbols. The modulation can use pulse position modulation and time hopping. A polarity of the pulses is inverted randomly before transmitting the pulses as an ultra wide bandwidth signal. By randomly inverting the polarity of the pulses spectral lines in the ultra wide bandwidth signal are eliminated.

The invention relates to a D-typed power amplifier, in particular to a D-type power amplifier and the input signal modulation technique. The invention discloses a D-typed power amplifier which can achieve balance between the system performance and the stability of the power amplifier and an input signal modulation method of the D-typed power amplifier. The D-typed power amplifier of the invention comprises a pulse density modulator, a pulse width modulator, a pulse molding circuit, a power magnify circuit and a low filter, and the pulse density modulator, the pulse width modulator, the pulse molding circuit, the power magnify circuit and the low filter are connected sequentially. The input signal modulation method of the D-typed power amplifier of the invention is: the signal is modulated in the pulse density aspect, the signal is modulated in the pulse width aspect, and the modulated signal is changed and is output to the power magnify circuit. The technical proposal of the invention is used for amplifying the power of the audio signal, thus efficiently improving the THD+N, SNR index and the power efficiency, and lowering the power magnify circuit of the switching frequency.

A variable gain amplifier device (100) with improved gain resolution is achieved. The device includes a programmable gain amplifier (PGA) (110), an analog-to-digital converter (ADC) (160), an automatic level control (ALC) algorithm means (176), and a delta-sigma modulator (180). The PGA (110) is capable to receive and to amplify an analog input signal (154) to thereby generate an analog output signal (164). The PGA (110) includes an amplifier (160) and a switchable resistor network (120). The ADC (170) is coupled to the PGA (110) and is capable to convert the analog output signal (164) to a digital signal (174). The ALC algorithm means (176) is coupled to the ADC (170) and is capable to generate a control code (178) by processing the digital signal (174). The delta-sigma modulator (186) is coupled to the ALC algorithm means (186) and is capable to generate a pulse-density modulated (PDM) signal (182) by processing the control code (178). The PDM signal (182) is fed back to the PGA (110) to control the switchable resistor network (120).

The invention provides an audio parametric array speaker system and a modulation method thereof. A pulse density modulation module is added in the system, and a signal having a follow-up processing function can be obtained. The method comprises the following steps of: performing carrier wave modulation, pulse density modulation, demultiplexing, direction adjustment and multi-direction signal superposition on digital audio signals, and transmitting ultrasound through an energy amplification and ultrasonic transduction array. Therefore, an outputted audio signal has functions of timely adjusting a direction and simultaneously playing sound in a plurality of strong directional directions. In addition, a digital signal system has the advantages of anti-interference, high integration and chip design.

The invention discloses an electronic cigarette circuit and an electronic cigarette. The electronic cigarette circuit comprises a capacitance-type microphone and an air flow detecting chip, wherein the capacitance-type microphone is configured to sense the air flow intensity, and output a corresponding air flow intensity signal according to the air flow intensity; the input end of the air flow detecting chip is connected with the output end of the capacitance-type microphone; and the air flow detecting chip is configured to provide work current for the capacitance-type microphone, and output apulse density modulation signal with the corresponding density according to the air flow intensity signal. With the technical scheme, the inhaling time and the air flow intensity generated during inhaling of a user can be detected.