585 results about "Audio power" patented technology

An audio power display provides a signal and an update rate. An audio power monitoring system comprises a digital display unit including at least one light-emitting display element and a rapid update rate. The digital display unit displays signal levels at the rapid update rate to emphasize the dynamic nature of music. In one embodiment, the display update rate is varied to increase proportionally to increases in signal level, and decrease proportionally to decreases in signal level to further represent the dynamic nature of music.

An energy-efficient consumer device audio power output stage provides improved battery life and reduced power dissipation. A power supply having a selectable operating mode supplies the power supply rails to the power amplified output stage. The operating mode is controlled in conformity with the audio signal level, which may be determined from a volume control setting of the device and/or from a signal level detector that determines the amplitude of the signal being amplified. The power supply may be a charge pump in which the operating mode uses a capacitive divider to provide for selection of a power supply output voltage that is a rational fraction of the power supply output voltage in a full-voltage operating mode.

An audio power management system manages operation of audio devices in an audio system. The audio power management system includes a parameter computer, a threshold comparator and a limiter. Audio signals generated with the audio system may be provided to the audio power management system. Based on a measured actual parameter of the audio signal, such as a real-time actual voltage and/or a real-time actual current, the parameter computer can derive estimated operational characteristics of audio devices, such as a loudspeaker included in the audio system. The threshold comparator may use the estimated operational characteristics to develop a threshold and manage operation of one of more devices in the audio system by monitoring the measured actual parameter, and selectively directing the limiter to adjust the audio signal, or another device in the audio system to protect or optimize performance.

An audio switching power amplifier having an output pulse voltage selected in conformity with an indication of the output signal amplitude provides lower electromagnetic interference (EMI) in class-D amplifier implementations, in particular, in inductor-less designs. The output pulse voltage may be selected by providing multiple switching circuits, such as half or fully bridge switches, with each switching circuit connected to a different power supply. One of the switching circuits is activated by the switching controller, while the others are disabled, providing selection of the output pulse voltage. Selection of a lower pulse voltage, when the maximum voltage is not required, reduces the generated EMI. The switching frequency of the class-D amplifier may also be controlled in conformity with the output signal amplitude, so that at higher output levels a lower switching rate is selected, reducing the generated EMI.

A charge pump power supply for an audio power amplifier integrated circuit has an operating mode selected according to an indication of operating environment and/or a process position of the integrated circuit. The operating mode selects the output voltage provided by the charge pump and may also select efficiency by selecting a frequency of operation of the charge pump and/or the effective size of a switching transistor bank. The selection is made in conformity with an indication of a process position of the integrated circuit and/or an indication of an environment of the integrated circuit, such as temperature, power supply voltage and/or load impedance values, and generally also in conformity with a volume (gain) setting, or a detected signal level, so that internal power consumption of the amplifier and charge pump is reduced when a high signal level is not being reproduced at the audio power stage.

A loudspeaker protection system includes a filter arrangement for defining one or more frequency bands of an audio signal, controllable amplifier/attenuator combinations coupled to the filter arrangement, and a processing arrangement coupled to control the amplifier/attenuator combinations, such as to determine audio power in at least one of the frequency bands representing relevant loudspeaker protection information used for selective audio power control in the at least one frequency band. This system has the features for a fast and/or slow thermal protection, as well as for a cone excursion protection, all for a loudspeaker in such a system.

A charge pump power supply for a consumer device audio power stage has an efficiency selected according to signal level. The frequency of operation of the charge pump and/or the effective size of a switching transistor bank is adjusted based upon a volume (gain) setting, or a detected signal level, so that internal power consumption of the charge pump is reduced when high output current is not required from the audio power stage and consequently from the charge pump. Operating modes of the charge pump are selected by the signal level indication and include at least a high power and a high efficiency mode selected by setting the charge pump operating frequency and/or enabling or disabling switching of one or more of multiple parallel transistors used to implement each switching element of the charge pump, thereby setting the level of gate capacitance being charged/discharged by the gate driver circuit(s).

There is disclosed a noise suppression device capable of improving the noise suppression accuracy while reducing the audio distortion. In this device, a suppression unit suppresses a noise component from the audio power spectrum by using the detection result of the audio-existing band and the noise band in the audio power spectrum including the noise component. A pitch harmonic structure extracting unit (105) extracts a pitch harmonic power spectrum from the audio power spectrum. An audio-existence judgment unit (106) judges whether the audio power spectrum has audio existence according to the extracted pitch harmonic power spectrum. A pitch harmonic structure repair unit (108) repairs the extracted pitch harmonic power spectrum. A per-band audio/noise correction unit (109) corrects the detection result according to the pitch harmonic power spectrum selected according to the result of judgment by the audio-existence judgment unit (106) among the repaired pitch harmonic power spectrum and the extracted pitch harmonic power spectrum.

The invention discloses a device which can restrain the transient noise of an audio power amplifier and can reduce or eliminate the click noise generated in the loudspeaker when the audio power amplifier is switched on or off, or enters or exits the standby mode. The technique proposal of the invention is that the device includes a noise restraining control signal generation module and a noise restraining module. In the noise restraining control signal generation module, a first input terminal receives standby mode enable signal; a second input terminal receives the power supply voltage; a first output terminal is connected with the output of the audio power amplifier and outputs the standby signal to the output of the audio power amplifier; a second output terminal outputs time sequence control signal. In the noise restraining module, the input of the module is connected with the second output terminal of the noise restraining control signal generation module to receive the time sequence control signal; a first output terminal is connected between the audio power amplifier and a blocking capacitor; a second output terminal is connected between the loudspeaker and the blocking capacitor to restrain the transient noise in the loudspeaker, which is generated by the audio transient signal output from the audio power amplifier. The device of the invention can be applied in the audio playing field.

In a fire alarm system, a message is sent on a pair of power lines to a notification appliance. The notification appliance responds to the message by activating one or more of its notification devices. In a standby mode, only enough power is supplied to the plural notification appliances, at a first voltage level, to support two-way communications between a system controller and the notification appliances. In an active mode, power is supplied at a second voltage sufficient to operate audible and visible alarms of the notification appliance. The notification appliance may include an addressable speaker. The addressable speaker connects to and receives messages over the pair of power lines, has plural taps for selecting audio power. In response to a command, a selector in an addressed smart speaker selects a tap to select a particular audio power.

A fully differential class D amplifier is provided. The class D amplifier includes an active amplifier in the feedback path of the modulator. In one embodiment, the class D amplifier includes a fully differential amplifier as an input buffer, in which a supply-independent reference voltage is used as the common mode voltage of the output of the fully differential amplifier. In one embodiment, the class D amplifier includes a pulse width modulation circuit that includes rail-to-rail comparators.

A method and apparatus for controlling a selectable voltage audio power output stage provides a mechanism for raising the selected power amplifier output voltage in time for the arrival of signal peaks to avoid clipping. Signal peaks may either be delayed by delaying an increase in volume control level or enabling signal compression for a predetermined time period, so that sufficient time is provided for the amplifier power supply to stabilize at a higher operating voltage when an increase of power supply voltage is selected. Alternatively, a signal level may be determined at an upstream source, such as a decoder or filter that provides information in sufficient advance of the arrival of the peaks, and used to control the power supply selection, so that the higher power supply voltage level is selected in advance of arrival of the signal peaks that would otherwise cause clipping at the power amplifier output.

A method and apparatus for power conversion in a class D amplifier is provided. The power conversion is achieved using synchronous rectifiers in a regulated half bridge power supply, taking the sum of the positive and negative rails as feedback, in order facilitate energy transfer between positive and negative output rails. This minimizes the effects of off side charging and rail sag, as well as achieving good line regulation, while allowing use of very small, low value output capacitors.

An audio power amplifier includes a differential amplifier circuit that serves as an input circuit. The differential amplifier circuit includes a signal ground terminal that receives a signal ground voltage, and an audio signal input terminal that receives an audio signal. A signal ground voltage generation circuit is provided to output the signal ground voltage. The signal ground voltage generation circuit includes a voltage follower amplifier that outputs a current, a reference voltage source that is input to the voltage follower amplifier, and a current control circuit that controls the current output from the voltage follower amplifier. The signal ground voltage rises in a prescribed manner while suppressing a pop sound during its transition.

An audio power unit is disclosed which provides an audio output and charges removable battery packs as well as providing a number of AC receptacles for powering other tools and the like when the unit is connected to a source of AC power. The unit can optionally also provide DC power. When the unit is connected to a source of AC power, the AC power drives the audio unit which may be a radio or a combination radio and CD player and the AC source also powers a charger which recharges a battery pack if a battery pack is inserted into the charger receptacle. If the unit is not connected to a source of AC power, the radio may be powered by a battery pack when it is placed in the charger receptacle. When the unit is connected to a source of AC power, a relay is opened to isolate the radio unit from the charger and battery pack. The unit has a unique protective frame structure that is connected to the housing of the unit.

An ultra-low profile vibrating transducer, particularly suited for floor mat and ultra thin vibrating pad and multimedia tactical feedback applications, using an “I” core coil in the center and permanent magnets positioned at both ends of the “I” core to create balanced push-pull vibrating actions. Mounting methods to effectively transfer energy to the users while withstanding user's body weight. “I” core coil may be driven by AC power, pulsed and/or DC power or audio power. Elastomeric supports are configured to provide rotational leverage action to further enhance the vibrating effectiveness.

The invention discloses an acoustical product with audio output power adjustable within a large range. The product is provided with a power supply voltage adjusting circuit, an audio power amplifying circuit, a current/voltage detection circuit and a controller. The current/voltage detection circuit detects current or voltage of an audio signal output through an audio power amplifier, generates a corresponding detection signal and outputs the signal to the controller; the controller judges whether the audio frequency signal output by the audio power amplifier is distorted or not according to the detected signal; if the audio frequency signal is distorted, the output power of the audio power amplifier is increased through the control mode of combining adjustment of gains of the audio power amplifier and adjustment of power supply voltage input to the audio power amplifier so as to drive a loudspeaker to send out sound normally. The output power of the audio power amplifier is comprehensively adjusted by adopting the two modes of gain adjustment and power supply voltage adjustment, and therefore the adjusting range of the audio output power is expanded, so that one type of acoustical product can drive loudspeakers of more types, and the different application requirements of the consuming public are met better.

The invention discloses a high-performance D type audio power amplifier adopting high-order multipath feedback structure, which comprises a prepositive variable gain amplifier, an integrator, a pulse width modulation (PWM) circuit, a three-state regulating circuit, a grid driving circuit and a power output stage. The integrator is in a two-order structure formed by cascade connection of two stages of integrators, and two paths of feedback are introduced to form a higher-order double-feedback loop, thereby effectively increasing the loop gain and the out-off-band attenuation, and obviously improving the suppression ratio of total harmonic distortion and noise to power sources and other main properties in the range of audio frequency band (22Hz-22KHz). By introducing two paths of voltage negative feedback and comprehensively considering the input dynamic range, the signal-to-noise ratio and stability factors, the ratio of two stages of feedback coefficients can be regulated by regulating the ratio of the input resistance and the feedback resistance of two stages of integrators, thereby ensuring the stability of a system. The D type audio power amplifier with the structure has the characteristics of high integration level and high performance and can be widely applied to the fields of portable equipment, consumer electronics and the like.

A solid stage audio power amplifier comprises of two output stages with one generating the real output signal that drives the real loud speaker load and the other mimicking the real output stage and generating a dummy output signal that drives a dummy resistor load. A frequency dependent feedback selection network, denoted as Feedback-Shifting network hereafter, is implemented between the two outputs and the input of the amplifier to fulfill a unique global feedback loop. In a particular embodiment, the Feedback-Shifting network can be constructed so that it receives more feedback information from the real output node than from the dummy output node at low frequencies, but less feedback information from the real output node than from the dummy output node at mid to high frequency bands. Such a power amplifier performs as a traditional solid state feedback amplifier at low frequencies by generating a clear and tight bass, but it sounds similar to an open loop tube amplifier at higher frequencies by reproducing natural mid-band and treble with less listening fatigue.

The invention discloses an automatic gain control circuit of an audio power amplifier, which comprises a fully differential operational amplifier and an automatic gain control circuit, wherein the in-phase and anti-phase input ends of the amplifier are provided with divider resistors respectively; feedback resistors are arranged between the in-phase input end and an output end as well as between the in-phase input end and the output end respectively; a biasing circuit is connected the fully differential operational amplifier; the input end of the control circuit is connected with the output end of the fully differential operational amplifier; a reference voltage circuit is connected with the control circuit; and the output end of the control circuit is connected with an adjustable resistor at the input end of the fully differential operational amplifier. In the invention, an output signal is compared with a reference voltage to obtain a digital signal, and the digital signal is used for controlling the front resistance value of the input end of the amplifier, so that a fixed gain can be kept for amplifying an audio signal during inputting of a small signal, closed-loop gain in the circuit is reduced during inputting of a large audio signal, and high linearity and low harmonic distortion of an output audio signal are ensured.

The invention provides a D class audio power amplifier, which comprises a preamplifier for amplifying an input audio signal; a PWM modulation circuit for modulating the amplified audio signal into a pulse signal; a logic control and drive circuit for carrying out logic control and drive on the pulse signal output from the PWM modulation circuit to output a drive signal; an output power stage circuit using the drive signal to drive a sound cell; and an anti-distortion module carrying out automatic gain control to change the gain of the preamplifier according to the audio signal amplified by the preamplifier.

An audio power conversion system includes a power supply having a positive supply rail and a negative supply rail for supplying power to a single ended class D amplifier. The system further includes a supply pump reduction circuit connected to the supply rails and adapted to redistribute a pumping charge from said power supply by forcing a current-flow from a rail with a higher voltage to a rail with a lower voltage. According to the at least one embodiment of the invention, the redistribution circuit is arranges to always distribute charge from the rail with the higher voltage. Thus, for practical circuits, the pump canceling occurs continuously and is not confined to every other cycle.

The invention discloses a acoustic power amplifier circuit for multiple audio source sharing, including output circuit of audio source, input circuit of differential audio power amplifier, feedback circuit of differential audio power amplifier, differential audio power amplifier, baseband processor and loudhailer. Series resistance for multiple audio source output, analogue switch is also included, wherein one end of series resistance for multiple audio source output is connected to corresponding output circuit of multiple audio source, which is used for receiving output audio signal from output circuit of multiple audio source and compensating output resistance; the other end of series resistance for multiple audio source output is connected to analogue switch, and the other end of analogue switch is connected to input circuit of differential audio power amplifier, wherein the analogue switch is used for switching series resistance for multiple audio source output to output audio signal of multiple audio source to differential audio power amplifier output circuit. The baseband processor is connected to analogue switch, which is used for analogue switch to control switching channel of audio signal of multiple audio source, and complete modulation and demodulation of baseband signal. The invention realize consistence of output volume from multiple audio source and adjustment range of the terminal device with low cost.