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| Number | Title | Issue Date |
| 8189817 | System for amplifiers with low distortion and low output impedance System for pulse-width-modulated class D audio amplifiers. In one preferred embodiment an adder is described to generate a difference signal responsive to an input signal and a feedback signal, a pulse-width-modulator coupled to the adder to compare the difference s... | 05/29/2012 |
| 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 of the audio signal, and the audio signal without the distorted volta... | 04/10/2012 |
| 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 invention utilizes a digital class D amplifier. Class D amplifiers are... | 04/20/2010 |
| 7368992 | Load-invariant amplifier A push-pull amplifier having low output impedance and low crossover distortion is provided. A least one of a current through a sourcing current path of an output stage and a current through a sinking current path of the output stage is determinative of a quiescent c... | 05/06/2008 |
| 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, providing a first diodes connected bi-directionally together with a first ... | 04/22/2008 |
| 7233199 | Circuit and method of establishing DC bias levels in an RF power amplifier A method and apparatus is used to provide DC stabilization and noise reduction in a multistage power amplifier. The invention uses various feedback techniques to stabilize DC levels, which helps to reduce noise. The invention also uses other techniques to reduce noi... | 06/19/2007 |
| 7146020 | Structure for the sound coil of loudspeaker An improved structure for the sound coil of loudspeaker comprises a cylinder provided with multiple layers of coils surrounding one end thereon. The coils are divided into sections in the middle position which provide more than two conducting wires. The cylinder is ... | 12/05/2006 |
| 7113045 | Power amplifier input structure having a differential output A method and apparatus provides an input structure for a power amplifier. In one example, the input structure has an input network and a predriver circuit to provide an input signal to the power amplifier. The input network includes a transformer for helping to main... | 09/26/2006 |
| 7113604 | Apparatus and method for matching the response of microphones in magnitude and phase An apparatus is provided for matching the response of a pair of microphones. The two microphones provide a first and second output, respectively, in response to an audible input. The microphone outputs are subtract from each other to produce a gain control output fo... | 09/26/2006 |
| 7016515 | Speaker apparatus In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/(2π×L1×(1−k | 03/21/2006 |
| 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 amplifier device drives the loudspeaker with a driving voltage. A feedback d... | 12/13/2005 |
| 6904158 | Speaker apparatus In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/{2 Π×L1×(1−k2) | 06/07/2005 |
| 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 terminal of the IC other than the external output terminal and a feedback ... | 09/14/2004 |
| 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. Each amplifier (10, 34) comprises a non-inverting input (... | 07/15/2003 |
| 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) and one com... | 05/13/2003 |
| 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 connected between the zero volt rail OV and a point intermediat... | 08/13/2002 |
| 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 switches (52, 53, and so on); the first switch (52) is con... | 06/18/2002 |
| 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 overcome the disadvantages of the prior art PWM amplifiers... | 10/09/2001 |
| 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 first increments. A unity gain second amplifier stage has... | 05/29/2001 |
| 6172561 | High volume expander circuit The present invention is directed to a circuit for performing volume expansion on an audio signal. The circuit includes an amplifier that has an input side and an output side. Further, the amplifier amplifies the audio signal at a first amplification to p... | 01/09/2001 |
| 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 processes. Feedback is included to provide enhanced gain, dy... | 12/12/2000 |
| 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 second output amplifiers (2) and (3) are added in an adde... | 10/03/2000 |
| 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, processed through the attack/release circuit, is used to ... | 04/11/2000 |
| 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 signals avoids the need for external components, reducing cost... | 03/07/2000 |
| 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 one frequency-response-determining RC member whose resisto... | 09/14/1999 |
| 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 during circuit turn-on. The amplifier has differential inputs... | 08/17/1999 |
| 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 measured signal. A sag control circuit receives the measure... | 06/01/1999 |
| 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 push-pull voltage gain/phase splitter stage. A bias adjustment ... | 09/29/1998 |
| 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 factor, employs a balanced feedback network having first an... | 08/18/1998 |
| 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 feedback input of the power amplifier circuit and the other en... | 07/28/1998 |
| 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 is isolated from the power amplifier section ground. The am... | 05/12/1998 |
| 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 amount of power delivered to the load from the amplifier. Th... | 02/17/1998 |
| 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 component, such as a Zener diode, LED, transistor junction or ... | 01/06/1998 |
| 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 turn-on. The amplifier is biased by a single power supply a... | 12/30/1997 |
| 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 circuits are provided in the respective output stage ampli... | 03/11/1997 |
| 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 terminals of each potentiometer are adapted for connection to... | 08/06/1996 |
| 5537081 | No turn-on pop noise amplifier An audio amplifier with no turn-on pop noise is achieved by the following features: (i) an input stage which operates under zero common-mode input voltage, (ii) an output stage which provides the low voltage end of its voltage swing very close to ground v... | 07/16/1996 |
| 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 second amplifying stage. The inputs to the current amplifie... | 03/21/1995 |
| 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 (popping) on the loudspeakers. For so doing, the circuit provide... | 11/08/1994 |
| 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 amplifier comprising an operational amplifier is suitable f... | 10/18/1994 |
