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8159292 |
Amplifying circuit
To efficiently obtain two outputs including one at a normal level and the other at an excessive level. An input signal input to the negative input terminal of an operational amplifier (14) having a...
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8155353 |
Device and method for driving speaker
Distortion caused in the voltage of an audio signal due to a back electromotive force generated due to loads in a speaker is detected, the detected distorted voltage is eliminated from the voltage...
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8130981 |
Sound card having feedback calibration loop
Disclosed are a sound card and a method for limiting inputs to and outputs from that computer sound card. Specifically, the voltage of a feedback connection between the input and output of a sound...
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8064622 |
Self-biased amplifier device for an electrecret microphone
A self-biased electrecret microphone amplifier with phantom biasing is using only standard devices implemented in a digital Complementary Metal Oxide Semiconductor (CMOS) process. The stable gain...
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8059837 |
Audio processing method and system
An audio processing system is provided. The audio processing system comprises a transducer, a gain stage, a capacitor network, and a preamplifier. The transducer transduces a sound signal to a...
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8054979 |
Audio system for improving a signal to noise ratio
An audio system performing a class-D amplification includes a first pulse width modulation (PWM) signal generation unit and a second PWM signal generation unit. The first PWM signal generation unit...
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8050423 |
Integrated circuit device and audio system
An n-channel integrated circuit device (n is an integer of 1 or greater) for muting an audio signal includes a control circuit configured to generate a control signal and a delayed control signal,...
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8045730 |
Methods and systems for reducing acoustic echoes in communication systems
Various embodiments of the present invention are directed to methods and systems that reduce acoustic echoes in audio signals in accordance with changing conditions at first and second locations...
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8040180 |
Operational amplifier capable of compensating offset voltage
An operational amplifier capable of compensating offset voltage includes an input stage circuit having a positive input end, a negative input end, a first current output end, and a second current...
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7925031 |
Audio system with feedback detection means
The invention concerns an audio system comprising a microphone, audio signal processing means, an output transducer and mans for detecting a possible feedback tone and the corresponding frequency...
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7912233 |
Speaker system for musical instruments
A speaker system for a musical instrument that detects the displacement of a voice coil of a speaker and provides feedback processing. The speaker system has a preamp that alters the frequency...
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7894616 |
Condenser microphone employing wide band stop filter and having improved resistance to electrostatic discharge
A condenser microphone employs a wide band stop filter, having improved resistance to electrostatic discharge. This includes providing a condenser microphone used for a multi-band by comprising a...
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7816980 |
Audio power amplifier using virtual ground and method of processing signal in the audio power amplifier
An audio power amplifier provides a virtual ground to reduce power on/off noise and a method for processing a signal in the audio power amplifier. The audio power amplifier includes a switching...
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7702120 |
Self-amplified loudspeakers with switching amplifier technology
The present invention utilizes switching power amplifier technology to improve the performance of self-amplified speaker system. In contrast to analog Class A and Class AB amplifiers, the present...
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7702119 |
Multi-input gain control circuit
A method and apparatus for selecting and mixing electronic signals. The circuit has an operational amplifier and two or more ganged, tapped-resistors in which the tap divides the resistance into a...
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7570714 |
Data transfer apparatus for low voltage differential signaling
A data transfer apparatus is composed of a transmitter and a receiver. The transmitter includes an output buffer developing a differential signal in response to a data signal, and an amplitude...
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7567908 |
Differential dynamic content delivery with text display in dependence upon simultaneous speech
Differential dynamic content delivery including providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; selecting...
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7362871 |
Audio amplifier circuit and audio IC having the same
In the present invention, in parallel with a resistor which determines an amplification rate being fed back from an output to an input of an output stage OP amp in an audio amplifier circuit,...
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6975734 |
Audio apparatus of negative driving with adaptive gain control
An audio apparatus is constructed for use in negative drive of a loudspeaker having an internal impedance to perform a desired amplitude-frequency characteristic. In the audio apparatus, an...
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6792121 |
Audio signal amplifier circuit and portable telephone set and portable electronic device using the same audio signal amplifier circuit
An audio signal amplifier circuit includes an external output terminal of an IC to which an output line of a power amplifier circuit is connected, a first resistor connected between a certain...
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6593809 |
Circuit for widening the stereobase in the reproduction of stereophonic sound signals
A circuit for widening the stereobase in the reproduction of stereophonic sound signals contains one amplifier (10, 34) each for the stereo signals assigned to the right-hand and left-hand channel....
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6563380 |
Dual bridge amplifier
In a dual bridge amplifier (1) for processing two input signals (Iin1; Iin2) and providing two amplified output signals (VL1; VL2) into two separate loads, comprising two signal amplifiers (10; 20)...
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6434243 |
Power amplifier
An output stage for a power amplifier comprises an amplifying device T1 connected in series with a variable current sink T2 between positive and negative supply rails +/−V. A loudspeaker S is c...
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6407633 |
Methods and apparatus for stabilizing feedback-controlled amplifiers
An apparatus (Z) having controllable impedance is inserted from output (22) to ground (23) of an audio-signal amplifier (20). Typically, the apparatus comprises a switch-chain (50) having multiple...
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6300825 |
PWM amplifier with feedback loop integrator
A PWM amplifier comprising a comparator and an integrator is known to amplify, for example, audio signals. One drawback of the known PWM amplifiers is the maximally achievable loop gain is low. To...
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6239655 |
Microphone amplifier with digital gain control
A remotely controlled microphone amplifier has a first amplifier stage with a variable gain circuit operatively connected in the overall feedback loop of the first stage for controlling the gain in...
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6160450 |
Self-biased, phantom-powered and feedback-stabilized amplifier for electret microphone
A self-biased electret microphone amplifier with phantom powering which avoids the need for JFETs and depletion mode devices, both of which are not standard devices when using BiCMOS fabrication...
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6127888 |
Power amplification device
There is disclosed a power amplification device for BTL-driving a load with a half-wave signal whose output direct current level is set close to an earth level, in which output signals of first and...
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6049618 |
Hearing aid having input AGC and output AGC
A hearing aid has input AGC and output AGC using only one attack/release circuit and only one variable gain amplifier. An input AGC signal and an output AGC signal are summed and the summed signal,...
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6035049 |
AC coupling and signal amplification using switched capacitors
AC coupling and signal amplification using switched capacitors. The use of a switched capacitor to simulate a resistor in amplifier coupling in an integrated circuit processing audio frequency...
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5953430 |
Filter circuit and audio signal processor provided therewith
A filter circuit adjustably decreases or increases the amplitude of audio signals in a predetermined frequency range. The filter circuit includes a filter module having an RC network with at least...
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5939938 |
Amplifier circuit with reduced DC power related turn-on and turn-off transients
An amplifier circuit with improved turn-on and turn-off transient operation includes a differential amplifier and a selectively variable reference generator for controlling the amplifier output...
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5909145 |
Variable control of electronic power supplies
Sag of a power signal delivered to of an amplifier is controlled. The maximum amount of sag is limited to limit crossover distortion. A measuring circuit monitors an observed signal to generate a...
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5815040 |
Wide bandwidth, current sharing, MOSFET audio power amplifier with multiple feedback loops
A wide bandwidth, multi-FET current sharing output stage, MOS audio power amplifier employs multiple feedback loops. An audio input is supplied to a voltage feedback amplifier stage driving a...
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5796305 |
Amplifier arrangements with high damping factor
A circuit for increasing damping factor in an audio amplifier adapted to be coupled to a load by output feed and return leads and components having an impedance causing a reduction in the damping...
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5787182 |
Audio signal amplifier circuit and a portable audio equipment using the same
The present invention resides in an audio amplifier circuit which includes an output terminal of an IC connected to a power amplifier circuit, a resistor having one end connected to a negative...
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5751823 |
Audio amplifier system with improved isolation between preamplifier and power amplifier
An audio amplifier, particularly suited for automotive applications, providing improved isolation between the preamplifier section and the power amplifier section. The preamplifier section ground...
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5719526 |
Internal load monitor for amplifier
A load monitor module for measuring voltage and current supplied from an amplifier to a load is provided within an amplifier and includes a device for calculating an impedance of the load and an...
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5705950 |
Hybrid solid state/vacuum tube audio amplifier
In this hybrid amplifier circuit the vacuum tube is direct coupled or DC coupled to the output of a solid state amplifier in a cathode follower configuration. An automatically operative bypass...
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5703529 |
Amplifier circuit with reduced DC power related transients
An amplifier circuit with improved turn-on transient operation includes a differential amplifier and a selectively variable reference generator for controlling the amplifier output during circuit...
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5610555 |
Low-voltage driven, audio signal amplifying apparatus and a portable acoustic system using said apparatus
The apparatus includes output stage amplifiers for receiving the respective outputs of preamplifiers provided in correspondence to the left and right channels in a stereo system. Negative feedback...
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5543759 |
Audio amplification circuits
An audio amplification circuit includes a ganged pair of logarithmic potentiometers, each potentiometer of the pair having an input terminal, an output terminal, and a wiper terminal. The input...
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5399986 |
Isolated multi-output power amplifier
A multi-output power amplifier is disclosed. The amplifier is divided into two stages. A single voltage amplifier is used as an input amplifying stage and several current amplifiers are used as a...
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5363062 |
Audio amplifier on-off control circuit
A circuit for controlling on-off switching of an audio amplifier in such a manner as to prevent sharp uncontrolled variations of the output during switching from resulting in undesired noise...
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5357214 |
Methods and apparatus for microphone preamplification
Preamplifying circuitry amplifies sound signals for input into a computer system. A first stage common-emitter amplifier provides high-gain amplification of the input signal, while a second stage...
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5343159 |
Direct box employing hybrid vacuum tube and solid state circuitry
The direct coupled solid state-vacuum tube hybrid circuit matches a high impedance audio source to a low impedance audio destination. The resulting device supplies essentially unit gain and has...
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5266905 |
Audio amplifier with amplified feedback
An audio amplifier with amplified feedback having a discrete component amplifier and an amplified negative feedback network. The amplified negative feedback network includes a feedback amplifier, a...
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5245296 |
Audio amplifier circuit and method of operation
An audio amplifier circuit which improves the efficiency, performance and power in a loudspeaker system. The circuit includes a discriminator differential amplifier which senses the motional...
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5227735 |
Technique to drive transformer coupled line amplifier
The invention relates to a circuit for driving a transformer coupled line amplifier. The present invention uses a high impedance differential negative feedback from the secondary of the transformer...
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5197099 |
Multiple-channel audio reproduction apparatus
A multiple-channel audio reproduction apparatus has an audio demodulator for demodulating an input signal to produce audio signals for multiple channels. One or more signal-processing circuits...
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