WO2004057754A1 - Procede et dispositif d'amplification efficace - Google Patents

Procede et dispositif d'amplification efficace Download PDF

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Publication number
WO2004057754A1
WO2004057754A1 PCT/IL2003/001059 IL0301059W WO2004057754A1 WO 2004057754 A1 WO2004057754 A1 WO 2004057754A1 IL 0301059 W IL0301059 W IL 0301059W WO 2004057754 A1 WO2004057754 A1 WO 2004057754A1
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WO
WIPO (PCT)
Prior art keywords
class
circuit
amplifier
frequency
signal
Prior art date
Application number
PCT/IL2003/001059
Other languages
English (en)
Inventor
Hanan Rumbak
Ron Shem-Tov
Original Assignee
Elop Electro-Optical Industries Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Elop Electro-Optical Industries Ltd. filed Critical Elop Electro-Optical Industries Ltd.
Priority to AU2003285740A priority Critical patent/AU2003285740A1/en
Publication of WO2004057754A1 publication Critical patent/WO2004057754A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H03F3/217—Class D power amplifiers; Switching amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/429—Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/432—Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier

Definitions

  • the invention relates generally to electronic and electric circuits and, more particularly, to efficient amplification of signals.BACKGROUND OF THE INVENTION
  • Class A amplifiers are electrically biased such that the active element of the amplifier (e.g., a transistor) is always in its linear region (i.e., never completely “on” or "off'). While Class A amplifiers provide high fidelity amplification, they dissipate significant power because the active elements of such amplifiers must be biased continually, even when there is no signal input to the amplifier. Thus, the theoretical maximum efficiency in a Class A amplifiers is very low.
  • Class B amplifiers involve two active elements in a "push-pull” arrangement, whereby one element drives the output while the other element sinks the output. Accordingly, when one element is “on”, the other element is “off. This arrangement improves the efficiency of the amplifier; however, when the signal being amplified is small, there may be times when neither of the elements is active, thereby producing crossover distortion.
  • Class AB amplifiers combine class A and class B circuitry. A small bias is supplied to each of the active elements thereby preventing them from being completely "off'. Thus, Class AB amplifiers feature less crossover distortion than class B amplifiers, and less power dissipation than in Class A amplifiers. By virtue of their reliable performance in amplifying high frequency signals, class AB amplifiers are the solution of choice in most low power or high-frequency applications. Still, the energy consumption of Class AB amplifiers is relatively high, as efficiency levels do not exceed 60 percent. Therefore, class AB amplifiers are generally not suitable for high-power applications.
  • a class D amplifier is a switching amplifier that converts a low-level analog input signal into a high power pulse-width modulated (PWM) output.
  • the switching frequency is much higher (at least ten times) the signal frequency, thereby permitting the high frequency components of the output signal to be removed by a simple filter.
  • the load is subjected to a full or half bridge of switches, which permit the load to be pushed or pulled, depending on whether the signal is positive or negative. Insofar as the switches dissipate a minimal amount of power, the Class D amplifier is highly efficient, and may reach efficiency levels of up to 97%.
  • Class D amplifiers have typically been used in low frequency (e.g., 20 kHz) and high power applications (e.g., in the kilo-Watts range), such as heavy motor control and high-power audio.
  • the "noisy" nature of class D amplifiers does not lend itself to high frequency/high fidelity applications, where small distortions may have a significant effect.
  • CTR cathode ray tube
  • “stroke” mode high frequency signals are amplified for short periods of time, accounting for a small part of the overall power usage.
  • symbols may be scanned onto the display during the vertical retrace period. This mode combines both high and low frequency symbols.
  • CRT devices To accommodate the high frequency of the "stroke” mode, such CRT devices must use the highly energy-consuming Class A, B or, typically, AB amplifiers. In both modes, the signal is amplified before being applied to the horizontal or vertical yoke to deflect the electron beam.
  • Embodiments of the present invention include an amplifier that can operate in two different ranges of frequencies, thereby combining the fidelity of class AB amplifiers for high frequencies with the efficiency of class D amplifiers for low frequencies.
  • a circuit is provided that combines the advantages of these amplifiers.
  • a power supply is provided that supplies substantially constant voltage irrespective of the current sourced or sinked by the load attached.
  • Fig. 1 is a block diagram of a circuit for amplifying a signal in accordance with exemplary embodiments of the invention.
  • Fig. 2 is a schematic diagram of a circuit for amplifying the current of a signal for an inductive load in accordance with some exemplary embodiments of the invention
  • Fig. 3 is a schematic diagram of a power supply/power controller circuit for driving a cathode ray tube (CRT) deflection device in accordance with exemplary embodiments of the invention.
  • CRT cathode ray tube
  • Fig. 4 is a schematic graph illustrating the gain of an amplifier in accordance with exemplary embodiments of the invention as a function of signal frequency.
  • Fig. 1 schematically illustrates an amplifier circuit in accordance with embodiments of the present invention.
  • a signal may be input into the amplifier circuit at input terminal 100.
  • a signal with frequency high enough to pass through the high-pass filter 110 is amplified by class AB amplifier 130 and out to output terminal 150.
  • a signal with frequency low enough to pass through the lowpass filter 120 is amplified by class D amplifier 140 and out to output terminal 150.
  • the high-pass filter 110 and low-pass filter 120 may, for example, be designed such that their gain is identical and/or such that the low cut-off frequency of highpass filter 110 and the high cut-off frequency of lowpass filter 120 are identical; however, this is not necessary if the closed feedback loop is employed.
  • the power signals as amplified by the two amplifiers are mixed at adder 170 and the resulting signal Sout is output to terminal 150.
  • the output signal is sensed, for example, by its voltage or current at sensor 160, and fed back to adder 180.
  • the amplification is properly distributed between the branches such that each branch operates as necessary depending on the signal frequency. In this way, the entire circuit may operate with a uniform gain for a continuous range of frequencies.
  • Variations of the basic circuit design of Fig. 1 may be used to amplify a signal supplied to various type of loads, for example, inductive, capacitive and resistive loads. For such loads, the embodiment may be modified to compensate for phase shift distortion, as described below.
  • the high-pass filter 120 and low-pass filter 130 may be comprised of multiple components (e.g., resistors, inductors, capacitors, etc.), or may be comprised of commercially available filters, depending on the desired results.
  • the elements comprising the high-pass filter 110 and low-pass filter 120 may be placed anywhere in the circuit and not necessarily in the relation to the class AB amplifier 130 and class D amplifier 140 as shown in Fig. 1.
  • Circuits according to embodiments of the present invention may be used to drive an inductive load, such as a deflection coil (yoke) of a cathode ray tube (CRT).
  • a CRT may have a "stroke on raster" mode, which combines both low and high frequency signals.
  • the present invention is therefore particularly suitable for amplifying deflection signals to a yoke in a CRT in that the signal to be amplified may be of high or low frequency.
  • the invention may also be suitable for any other system or device in which signals of varying frequency ranges, or a wide range of frequencies, are amplified to provide more power efficient amplification.
  • the efficiency of class D amplifiers can be used in a CRT by amplifying only signals of sufficiently low frequencies, for which the PWM noise is insignificant.
  • a class AB amplifier circuit is used for the high frequency signals.
  • the present invention integrates two amplification functions into one device and, therefore, the invention may also reduce the size and cost of circuitry associated with the device using the invention.
  • an embodiment of the present invention may use a class D amplifier to amplify deflection signals at both low frequencies, e.g., for "sweep" mode deflection signals at frequencies on the order of approximately 5 kHz and 50-60 Hz, and a class AB amplifier to amplify high frequencies, e.g., for "stroke" mode deflection signals at frequencies on the order of approximately 100-2000 kHz.
  • Fig. 2 schematically illustrates an amplification circuit in accordance with embodiments of the invention.
  • a circuit similar to that shown in Fig. 2 may be used for each of the horizontal and vertical deflection signal amplification circuits of a CRT.
  • the characteristics of the elements chosen may vary depending on the different expected frequencies of the deflection input signal and on the desired power gain.
  • some circuit components may be added or omitted as necessary for a particular application. It should be appreciated that the applicability of the circuit of Fig. 2 is not limited to CRT applications, and similar circuits may be used in conjunction with any other application where signal amplification based on frequency discrimination may be advantageous.
  • the circuit according to the embodiment of Fig. 2 receives an input signal at terminal 302 and produces a uniformly amplified, high-fidelity output signal at the CRT yoke or deflection coil 336.
  • a signal of low frequency or DC is amplified predominantly through the class D amplifier 318, whereas a signal of high frequency is amplified predominantly through the class AB amplifier 312.
  • the circuit as shown ensures that the gain at the CRT is substantially constant regardless of whether one amplifier or the other, or both, is in operation.
  • the circuit may be equipped with an error amplifier 306.
  • the error amplifier 306 receives an input responsive to the sum of the current passing through resistor 304 and the current passing through resistor 332 and capacitor 352 (representing the output signal to the CRT 336, which is 180° out of phase with the input signal).
  • the resistance of resistor 334 may be decreased and an operational amplifier 350 may be added.
  • the sum of these currents, representing the error of the amplification is amplified by error amplifier 306.
  • the signal output from error amplifier 306 is diverted to the class D or class AB amplifier subcircuit, or a combination of both, based on its frequency.
  • the deflection signal is of a sufficiently high frequency, e.g., greater than frequency f1
  • the signal will be amplified by a class AB amplifier 312.
  • Resistor 310 and a capacitor 308 are arranged in a high-pass arrangement according to principles known in the art.
  • Frequency f1 is the frequency for which the current output from the class AB branch is equal to the output of the class D branch. At frequencies greater or less than f1 , the two branches operate together in a ratio of current outputs determined by the signal frequency.
  • the components that determine frequency f1 include 310, 348, 314, 316, 320, 326 and 308.
  • High impedance elements 348 and 326 are added to the branches in order to add the currents from the two branches together.
  • Capacitor 362 may be added in parallel to inductor 326 as a trap for the modulating frequency of the class D amplifier, thus reducing output noise of the amplifier.
  • Components 324 and 338 may be used to stabilize the class D branch at higher frequencies.
  • any high frequency input signal is amplified predominantly by the class AB amplifier 312, and any low frequency input signal is amplified predominantly by class D amplifier 318.
  • the amplified signal is received at the CRT deflection coil 336, and sent to ground via resistor 334. This current is sampled as part of the feedback loop to the error amplifier 306. If an operational amplifier 350 is used, its gain multiplied by the resistance of resistor 334 represents a new, typically higher, effective resistance
  • phase-shift error should be corrected at those high frequencies. This may be done, as shown in the embodiment of Fig. 2, by resistor 328 and capacitor 330, as well as by capacitor 340 and resistor 342. These elements, in combination, function to correct the phase shift distortion that may be introduced at higher frequencies. Due to the high impedance of the capacitors at low frequencies and DC voltages, the phase-shift correction components do not affect performance at low frequencies.
  • the function of optional switch 364, capacitor 366 and resistor 368 is discussed below with regard to shifting the cut-off frequency of the amplifier.
  • resistor 324 and capacitor 338 provide low impedance at high frequencies, thereby diverting current from inductor 326, stabilizing the class D subcircuit 358 at such high frequencies, and limiting the contribution of class D sub-circuit 358 to the current at the deflection coil 336.
  • resistor 348 and capacitor 314 provide high impedance at low frequencies, thereby decreasing current from class AB subcircuit 356, stabilizing the class AB subcircuit 356 at low frequencies, and limiting the contribution of class AB sub-circuit 356 to the current at the deflection coil 336.
  • the horizontal deflection signal requires retrace of the electron beam at a high rate (i.e., high retrace ratio) and a high current that is typically beyond the capabilities of the overall amplifier configuration due to present technological limitations. Therefore, in an amplifier circuit used to amplify the horizontal deflection signal, switches 352 and 354 may be inserted to prevent the amplifiers from such overload. During normal operation, switches 352 and 354 are closed; however, during rapid retrace, the switches are open and capacitor 360 is charged, creating a half-sine wave at a frequency determined by the characteristics of capacitor 360 and deflection coil 336. Switch 354 helps minimize power loss during retrace. The action is similar to a pendulum, in which the power stored in the deflection coil at the end of a line scanned serves to return the electron beam approximately back to the starting point. This technique is known and used in nearly all televisions produced today.
  • capacitor 352 may serve to compensate and restrain this tendency to instability created by the parasitic capacitances.
  • Inductor coil 344 and capacitor 346 operate as a lowpass filter to eliminate the modulation frequency of the class D amplifier.
  • the components should be chosen so as not to narrow the bandwidth of the amplifier. As these components transmit great amounts of power in short periods of time, they should preferably be high quality components, such as NPO/COG capacitors.
  • the current passing through resistor 334 represents the sum of currents put out by both the amplifier branches, which is fed back to error amplifier 306 serving the entire circuit operating as a whole.
  • the result of the feedback loop taking its input from the two amplifier branches is a unified closed circuit that operates as one amplifier with an overall gain.
  • the class D amplifier may operate in a full bridge or half bridge configuration.
  • a full bridge configuration one power supply suffices to provide the amplifier with power; however, the power required to activate the switching elements in this configuration tends to decrease the overall efficiency of the amplifier due to the use of two pairs of switching elements.
  • a half bridge configuration it is convenient to have both positive and negative power supplies connected to the amplifier.
  • the power required to activate the switching elements tends to decrease the overall efficiency of the amplifier.
  • any power supply adequate for the class D amplifier may be used.
  • One power supply/power controller circuit that may be used to supply a steady voltage relatively irrespective of the current being sourced or sunk is described in Fig. 3.
  • One purpose of the power supply described in Fig. 3 is to convert a floating voltage (Vcc) into positive and negative voltages relative to a ground.
  • Vcc floating voltage
  • each of these voltage sources i.e., positive and negative, should be able to supply current and receive excess current without varying its voltage.
  • excess current to one voltage supply does not become wasted, e.g., become dissipated as heat, but rather is passed through to charge the other voltage supply, thereby optimizing efficiency.
  • the voltage divider comprised of resistors 408 and 410 divides the floating DC voltage Vcc at terminals 400.
  • the PWM controller 402 may operate to open and close switches 404 and 406, such that the two are never closed simultaneously.
  • stable voltages relatively irrespective of current sourced or sinked may be obtained at terminals 418 and 420. Specifically, if the current across capacitor 416 becomes greater than the current across capacitor 414, capacitor 416 discharges while the voltage potential between terminals 418 and 420 remains constant Vcc.
  • the voltage divider comprising resistors 408 and 410 alters the duty cycle of the PWM controller such that switch 404 is closed for longer durations, thereby compensating for the imbalance.
  • inductor 412 is charged.
  • switch 406 is closed, the charged inductor discharges across capacitor 416.
  • the charge stored across capacitor 414 is transferred to capacitor 416 using inductor 412 and switches 404 and 406.
  • the theoretical basis for the efficiency is that the energy across one capacitor, i.e., CV 2 /2, is transferred to the inductor, i.e., LP/2, and then to the other capacitor.
  • the difference between the voltages at terminals 418 and 420 is Vcc.
  • the duty cycle established by the PWM controller determines the values of Vpos at terminal 418 and Vneg at terminal 420.
  • the embodiment of the power supply described provides a substantially constant voltage for power within an operating range.
  • PWM controller 402 may be a commercially available controller for a class D amplifier; inductor 412 may be 10 ⁇ H; capacitors 414 and 416 may be 100 ⁇ F; resistors 408 and 410 may be 10k ⁇ .
  • a half bridge was chosen due to considerations of efficiency and simplicity. Thus, positive and negative power supplies are provided that need to work in both source and sink mode. It will be appreciated by those of skill in the art that alternatively, a full bridge or other configuration may be employed with similar effect in accordance with the present invention. Alternately, those of skill in the art will recognize that a full bridge may be used, accompanied by appropriate alterations in the circuitry.
  • a circuit for amplification of both horizontal and vertical deflection signals may be constructed by combining two circuits such as shown in Fig. 2, one for each input signal (Xin and Yin) and each having a separate output signal across the appropriate yoke or deflection coil (Xout across the horizontal deflection coil and Yout across the vertical deflection coil).
  • both class D amplifiers may be controlled by a single power supply/power controller as shown in Fig. 3.
  • the resultant overall gain of the amplifier of Fig. 2 is illustrated schematically in Fig. 4.
  • the amplification of the subcircuit containing the class D amplifier is shown by curve 500, where f1 is the frequency at which the amplification by the class D subcircuit is halved.
  • the amplification of the subcircuit containing the class AB amplifier is shown by curve 502, where f1 and f2 are frequencies at which the amplification by the class AB subcircuit is halved.
  • the cut-off frequency may be shifted, for example, from f2 to lower frequency f2', as shown in Fig. 4, thereby narrowing the bandwidth of the amplifier.
  • This may optionally be accomplished, for example, as shown in Fig. 2, by placing an impedance, such as resistor 368 and capacitor 366, in parallel with capacitor 340 and resistor 342.
  • this additional impedance may be selectively connectable, for example, by switch 364, which may control shifting cut-off frequency f2 to f2'.
  • the additional impedance may optionally be altered to variably adjust the cut-off frequency.
  • Embodiments of the present invention may include other apparatuses for performing the operations herein. Such apparatuses may integrate the elements of the amplifiers discussed, or may comprise alternative components to carry out the same purpose. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims, which follow:

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

L'invention concerne un circuit utilisant les avantages d'un amplificateur classe AB dans les hautes fréquences ou les basses puissances et d'un amplificateur classe D dans les basses fréquences ou les hautes puissances.
PCT/IL2003/001059 2002-12-23 2003-12-11 Procede et dispositif d'amplification efficace WO2004057754A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003285740A AU2003285740A1 (en) 2002-12-23 2003-12-11 Method and apparatus for efficient amplification

Applications Claiming Priority (2)

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US43534302P 2002-12-23 2002-12-23
US60/435,343 2002-12-23

Publications (1)

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WO2004057754A1 true WO2004057754A1 (fr) 2004-07-08

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006111892A2 (fr) * 2005-04-20 2006-10-26 Nxp B.V. Amplificateur lineaire et convertisseur cc-cc agences en parallele
WO2011115649A1 (fr) * 2010-03-16 2011-09-22 Motorola Solutions, Inc. Boucle de rétroaction avec chemins vers l'avant parallèles
CN102299688A (zh) * 2010-06-22 2011-12-28 炬力集成电路设计有限公司 一种音频功率放大器及音频功放模式切换方法
CN102355204A (zh) * 2011-05-20 2012-02-15 深圳市纳芯威科技有限公司 一种音频功放自动切换电路及功放芯片
WO2012131282A1 (fr) * 2011-04-01 2012-10-04 Hawkeshead Designs Ltd Amplificateur
US8964892B2 (en) 2011-08-23 2015-02-24 Motorola Solutions, Inc. Apparatus and method for operating a transmitter
FR3023089A1 (fr) * 2014-06-30 2016-01-01 Devialet Amplificateur audio tres haute fidelite
US9917557B1 (en) 2017-04-17 2018-03-13 Cirrus Logic, Inc. Calibration for amplifier with configurable final output stage
US9929703B1 (en) 2016-09-27 2018-03-27 Cirrus Logic, Inc. Amplifier with configurable final output stage
US10284217B1 (en) 2014-03-05 2019-05-07 Cirrus Logic, Inc. Multi-path analog front end and analog-to-digital converter for a signal processing system
CN110582935A (zh) * 2017-04-07 2019-12-17 思睿逻辑国际半导体有限公司 在具有多个回放路径的音频系统中进行切换

Citations (5)

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Publication number Priority date Publication date Assignee Title
US3733514A (en) * 1971-03-19 1973-05-15 Tektronix Inc Wide band amplifier having two separate high and low frequency paths for driving capacitive load with large amplitude signal
US4346349A (en) * 1979-05-10 1982-08-24 Nippon Gakki Seizo Kabushiki Kaisha Multi-channel audio power amplifier
US5170132A (en) * 1990-09-14 1992-12-08 Sextant Avionique Chopper amplifier circuit for the supply of a current proportional to a voltage
US5617306A (en) * 1995-03-02 1997-04-01 The Regents Of The University Of California One cycle control of bipolar switching power amplifiers
WO2002015387A2 (fr) * 2000-08-17 2002-02-21 Ericsson Inc Systemes et techniques d'amplification utilisant des tensions d'alimentation fixes et modulees et une commande de devoltage-survoltage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3733514A (en) * 1971-03-19 1973-05-15 Tektronix Inc Wide band amplifier having two separate high and low frequency paths for driving capacitive load with large amplitude signal
US4346349A (en) * 1979-05-10 1982-08-24 Nippon Gakki Seizo Kabushiki Kaisha Multi-channel audio power amplifier
US5170132A (en) * 1990-09-14 1992-12-08 Sextant Avionique Chopper amplifier circuit for the supply of a current proportional to a voltage
US5617306A (en) * 1995-03-02 1997-04-01 The Regents Of The University Of California One cycle control of bipolar switching power amplifiers
WO2002015387A2 (fr) * 2000-08-17 2002-02-21 Ericsson Inc Systemes et techniques d'amplification utilisant des tensions d'alimentation fixes et modulees et une commande de devoltage-survoltage

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006111892A2 (fr) * 2005-04-20 2006-10-26 Nxp B.V. Amplificateur lineaire et convertisseur cc-cc agences en parallele
WO2006111892A3 (fr) * 2005-04-20 2007-01-11 Koninkl Philips Electronics Nv Amplificateur lineaire et convertisseur cc-cc agences en parallele
WO2011115649A1 (fr) * 2010-03-16 2011-09-22 Motorola Solutions, Inc. Boucle de rétroaction avec chemins vers l'avant parallèles
US8229372B2 (en) 2010-03-16 2012-07-24 Motorola Solutions, Inc. Parallel forward path cartesian feedback loop and loop filter with switchable order for cartesian feedback loops
CN102299688A (zh) * 2010-06-22 2011-12-28 炬力集成电路设计有限公司 一种音频功率放大器及音频功放模式切换方法
WO2012028017A1 (fr) * 2010-06-22 2012-03-08 炬力集成电路设计有限公司 Amplificateur de puissance audio et procédé de commutation entre modes d'amplification de puissance audio
CN102299688B (zh) * 2010-06-22 2014-04-09 炬力集成电路设计有限公司 一种音频功率放大器及音频功放模式切换方法
WO2012131282A1 (fr) * 2011-04-01 2012-10-04 Hawkeshead Designs Ltd Amplificateur
CN102355204A (zh) * 2011-05-20 2012-02-15 深圳市纳芯威科技有限公司 一种音频功放自动切换电路及功放芯片
CN102355204B (zh) * 2011-05-20 2014-04-16 深圳市纳芯威科技有限公司 一种音频功放自动切换电路及功放芯片
US8964892B2 (en) 2011-08-23 2015-02-24 Motorola Solutions, Inc. Apparatus and method for operating a transmitter
US10284217B1 (en) 2014-03-05 2019-05-07 Cirrus Logic, Inc. Multi-path analog front end and analog-to-digital converter for a signal processing system
FR3023089A1 (fr) * 2014-06-30 2016-01-01 Devialet Amplificateur audio tres haute fidelite
WO2016001253A1 (fr) * 2014-06-30 2016-01-07 Devialet Amplificateur audio très haute fidélité
US10483914B2 (en) 2014-06-30 2019-11-19 Devialet Very high fidelity audio amplifier
US9929703B1 (en) 2016-09-27 2018-03-27 Cirrus Logic, Inc. Amplifier with configurable final output stage
WO2018063878A1 (fr) * 2016-09-27 2018-04-05 Cirrus Logic International Semiconductor, Ltd. Amplificateur comportant un étage de sortie final configurable
US10447217B2 (en) 2016-09-27 2019-10-15 Cirrus Logic, Inc. Amplifier with configurable final output stage
CN110582935A (zh) * 2017-04-07 2019-12-17 思睿逻辑国际半导体有限公司 在具有多个回放路径的音频系统中进行切换
CN110582935B (zh) * 2017-04-07 2021-08-24 思睿逻辑国际半导体有限公司 在具有多个回放路径的音频系统中进行切换
US9917557B1 (en) 2017-04-17 2018-03-13 Cirrus Logic, Inc. Calibration for amplifier with configurable final output stage

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