WO2004015855A1 - ボリューム調整装置、デジタルアンプおよびデジタル信号再生装置 - Google Patents
ボリューム調整装置、デジタルアンプおよびデジタル信号再生装置 Download PDFInfo
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- WO2004015855A1 WO2004015855A1 PCT/JP2003/009504 JP0309504W WO2004015855A1 WO 2004015855 A1 WO2004015855 A1 WO 2004015855A1 JP 0309504 W JP0309504 W JP 0309504W WO 2004015855 A1 WO2004015855 A1 WO 2004015855A1
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- voltage
- power supply
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- value
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- 230000005236 sound signal Effects 0.000 claims description 45
- 239000003990 capacitor Substances 0.000 claims description 40
- 230000003321 amplification Effects 0.000 claims description 29
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 29
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- 238000012986 modification Methods 0.000 description 2
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Classifications
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- 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
- H03F3/2173—Class D power amplifiers; Switching amplifiers of the bridge type
-
- 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
- H03F3/2171—Class D power amplifiers; Switching amplifiers with field-effect devices
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G1/00—Details of arrangements for controlling amplification
- H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
- H03G1/0088—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using discontinuously variable devices, e.g. switch-operated
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/004—Control by varying the supply voltage
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
- H03G3/301—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable
- H03G3/3021—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable by varying the duty cycle
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/331—Sigma delta modulation being used in an amplifying circuit
Definitions
- the present invention drives a switching element using a pulse density modulation (PDM) signal or a pulse width modulation (PWM) signal, and performs high-efficiency power amplification of an audio signal by using the switching element in a saturation region.
- PDM pulse density modulation
- PWM pulse width modulation
- the above-described high efficiency power amplifier is configured to adjust the amplitude of the signal at the signal source by a volume control method, or in an amplification unit that amplifies a 1-bit digital signal after delta sigma modulation. It can be divided into configurations for adjusting the signal amplitude.
- FIG. 8 shows a high efficiency power amplifier according to the former configuration
- FIG. 9 shows a high efficiency power amplifier according to the latter configuration.
- the digital audio signal output from the digital signal source 101 is ⁇ modulated by the ⁇ ⁇ modulation circuit 102 to become a 1-bit digital signal, and the gate drive It is supplied to the circuit 10.
- the gate drive circuit 103 outputs a gate drive signal based on the 1-bit digital signal to drive a power MOSFET which constitutes an output full bridge circuit 104.
- output full latch circuit 1 • 0 4 power amplified 1 by switching operation of power MO SF ⁇ 1 1 A bit digital signal is obtained.
- the amplified 1-bit digital signal is converted into an analog audio signal by passing through a low-pass filter 105, and output as an audio signal by an output device 106 such as a headphone. .
- the amplitude adjustment signal provided by the microcomputer 107 controls the amplitude of the audio signal in volume step units in the digital signal source 101.
- the fixed voltage supply 108 applies a constant power supply voltage to its power supply terminal, so that the amplitude adjustment of the 1-bit digital signal is not performed.
- the amplitude adjustment of the audio signal in the digital signal source 101 is not performed, but the variable power supply is controlled by the power supply control voltage of the analog port provided by the microcomputer 107.
- the power supply voltage of 1 0 9 is controlled in volume setting steps.
- a variable power supply voltage controlled by the fixed voltage power supply 109 is applied to the power supply terminal thereof, whereby a 1-bit digital signal is generated. Is adjusted in amplitude.
- the amplitude level (input level) of the input signal from the digital signal source 101 is constant, and as indicated by the mouth and 0.
- the level of the power supply voltage of the variable voltage power supply 109 and the amplitude level (output level) of the output of the output full bridge circuit 104 almost change.
- FIG. 11 is a block diagram showing a configuration of a prior art digital amplifier 201 as a high efficiency amplifier similar to the configuration of FIG.
- This digital amplifier 2 0 1 is an analog audio signal, ⁇ ⁇ block 2
- power amplification is performed by an output transistor Q2 0 1, Q 2 composed of an NMO SFET interposed between a high level power supply line 2 0 6 and a single level power supply line 2 0 7.
- the pull-pull operation is performed by a series circuit of 202 and a series circuit of output transistors Q 2 0 3 and Q 2 0 4 composed of NMO SFETs. The operation of the output transistors Q 2 0 1 to Q 2 0 4 in the saturation region enables highly efficient power amplification as described above.
- a 1-bit signal from the ⁇ block 202 is input to the upper gate drive circuit 220, and the positive phase component and the negative phase component generated here generate the output transistors Q 2 0 1, Q 2. 2 0 3 is driven.
- the other one-bit signal from ⁇ ⁇ ⁇ 2 0 2 is the lower gate drive circuit 2
- the output transistors Q 2 0 2 and Q 2 0 4 are driven by the positive phase component and the negative phase component which are input to 0 9 and generated here.
- the pair of output transistors Q 2 0 1 and Q 2 0 4 of the diagonal lines are driven in phase by these gate drive circuits 2 0 8 and 2 0 9, and the set of output transistors Q 2 0 2 and Q 2 0 3 Are driven in the same phase, and the set of the output transistors Q 2 0 1 and Q 2 0 4 and the set of the output transistors Q 2 0 2 and Q 2 0 3 are driven in the opposite phase to each other, and the push-pull operation is performed. Is realized.
- the variable DC power supply voltage V 0 0 from the variable voltage power supply 2 10 is input to the drains of the output transistors Q 2 0 1 and Q 2 0 3 via the power supply line 2 0 6.
- the sources of the output transistors Q 2 0 2 and Q 2 0 4 are brought to the GND level via the power supply line 2 0 7.
- the connection point between the source of the output transistor Q201 and the drain of the output transistor Q202 and the connection point between the source of the output transistor Q203 and the drain of the output transistor Q204 are output ends. And are connected to the positive phase output end P 2 0 1 and the negative phase output end P 2 0 2 via the low pass filters 2 0 3 and 2 0 4, respectively.
- a load resistance R 2 0 1 is inserted between the output terminals P 2 0 1 and P 2 0 2.
- the low-pass filters 203 and 204 are composed of coils L201 and L202 and capacitors C201 and C202.
- a PWM signal that switches between the Vcc level and the GND level is input to the variable voltage power supply 210 from the power supply input terminal TOO.
- a voltage according to the duty of the PWM signal is outputted. This voltage is output via the power supply line 2 0 6 to the output transistor Q 2 0 1 Power supply voltage V 0 0 is input to the Q 2 0 3 drain.
- the low pass filter 21 1 comprises a coil L 2 0 3 and a capacitor C 2 0 3.
- a DC power supply voltage V 0 1 from a fixed voltage power supply (not shown) supplied to the power supply input terminal T 0 1 is input to the upper gate drive circuit 2 0 8.
- the lower gate drive circuit 2 0 9 receives a DC power supply voltage V 0 2 from a fixed voltage power supply (not shown) supplied to the power supply input terminal T 0 2.
- the power consumption is generally It was set to be the same as the large volume (no known data and no data).
- the power supply voltage of the output bridge circuit 104 it is conceivable to lower the power supply voltage of the output bridge circuit 104.
- the reduction of the supply voltage lowers the output level, which causes a disadvantage that the maximum output (maximum volume) also decreases.
- variable voltage power supply 1 0 9 In the configuration of Fig. 9, the level of the power supply voltage of variable voltage power supply 1 0 9 almost matches the amplitude level (output level) of the output of full output bridge circuit 1 0 4 The power consumption is not always in a large volume state as in the configuration shown in FIG. However, in the configuration shown in FIG. 9, since the variable voltage power supply 1 0 9 generally has a servo circuit configuration, the servo gain can not be obtained at the time of low voltage output. This has been supplied to switching amplification means, causing a decrease in audio performance such as an increase in distortion, a decrease in SZN, and an increase in residual noise. An example of distortion data at this time is shown in the graph of FIG. As shown by the symbol ⁇ in the figure, in the range where the output polygon value is small, the distortion ratio increases as the output volume value decreases.
- the digital amplifier 201 reduces the duty of the WM signal to the power input terminal TOO as described above, whereby the power level actually supplied to the speaker, that is, the output drive circuit 5 5
- the power consumption in the remaining circuits is the same as in the large volume. This is the same as in the configuration of FIG. 9.
- the power consumption in the gate drive circuit 103 at the small volume is the same as at the large volume.
- the present invention has been made in view of the above problems, and has as its main object to reduce power consumption at the time of small volume in a digital amplifier.
- the present invention is further directed to improving audio performance in digital amplifiers. Disclosure of the invention
- the drive circuit drives the switching element in response to the audio signal converted into the 1-bit signal, and the power supply voltage is switched.
- variable drive voltage generation means for generating the variable power supply voltage, and the drive voltage of the switching element by the drive circuit is changed in conjunction with the change of the power supply voltage.
- driving voltage changing means for generating the variable power supply voltage, and the drive voltage of the switching element by the drive circuit is changed in conjunction with the change of the power supply voltage.
- the power supply voltage of the digital amplifier can be changed by the variable power supply voltage generation circuit to change the output amplitude, and according to this, the drive voltage changing means performs switching of the gate voltage of the MOSFET and the like.
- the drive voltage of the device is also changed. That is, for example, when the power supply voltage is high, the drive voltage is also high, and when the power supply voltage is low, the drive voltage is also low.
- the on-time gate voltage is always maintained higher than the source voltage by a predetermined voltage.
- the drive voltage can be made the minimum necessary voltage without affecting the switching operation of the switching element, and the power consumption of the drive circuit at the time of small output amplitude can be reduced.
- the variable power supply voltage generating means smoothes a pulse width modulation signal formed by switching a predetermined DC voltage with variable duty in order to create a variable power supply voltage to the switching element.
- the switching output of the DC power supply is at a low level, For example, when it is at the GND level, the potential of one terminal of the capacitor also becomes the G ND level, and the potential of the other terminal of the capacitor becomes the constant voltage V 1 via the diode, and the capacitor is charged.
- the switching output of the DC power supply becomes high level, for example, Vcc level
- the potential of one terminal of the capacitor also becomes Vcc level
- the potential of the other terminal of the capacitor becomes Vcc + V 1.
- V 0 + V 1 is obtained, where V 0 is the changed supply voltage from the DC power supply. That is, power supply voltage V 0 is a potential obtained by smoothing two potentials Vcc / GND with a low pass filter, and changes according to the duty.
- Another volume control apparatus is a volume control apparatus for controlling an amplitude of an output signal output from an amplifier having an amplification means for switching and amplifying a 1-bit audio signal.
- Amplitude variable means for changing the amplitude of the audio signal before being converted to a bit signal to a designated magnification size
- voltage variable means for changing the power supply voltage applied to the amplification means to a designated voltage value
- the amplitude of the output signal is set between the maximum value and the middle value.
- the constant magnification set by the setting control means and the voltage value corresponding to the input volume value are respectively given as the amplitude varying means and the voltage varying means.
- an audio signal having a constant amplitude according to the magnification is output from the amplitude varying means, for example, converted into a 1-bit signal by the ⁇ modulation circuit, and then switching amplified by the amplification means.
- switching amplification means that the amplitude of a 1-bit signal is amplified by driving a plurality of switching elements with a drive signal generated based on a 1-bit signal and switching the power supply voltage.
- the power supply voltage applied to the amplification means is outputted from the voltage variable means as a voltage value corresponding to the input volume value. Therefore, the amplitude of the output signal from the amplification means is adjusted by the supply voltage. As a result, the power supply voltage is lowered as the amplitude of the output signal is adjusted so as to approach the maximum value from the middle value, and the current consumption in the amplitude means is accordingly reduced.
- the amplitude of the output signal is set between the intermediate value and the minimum value, the constant voltage value set by the setting control means and the scaling factor according to the input volume value are respectively the voltage variable means and Amplitude changing means is provided.
- an audio signal having an amplitude corresponding to the input volume value is output from the amplitude varying means, converted to a 1-bit signal, and then switched and amplified by the amplifying means.
- the power supply voltage applied to the amplifying means is outputted from the voltage varying means as a constant voltage value. Therefore, the amplitude of the output signal from the amplification means is adjusted by the scaling factor.
- the power supply voltage does not change, so that the servo can operate stably in the voltage variable means comprising the servo type variable power supply device. Stable output of the power supply voltage by it can.
- deterioration of audio performance such as distortion factor is suppressed by the provision of a stable power supply voltage.
- the setting control means has a storage means for storing the magnification ratio and the voltage value corresponding to the input volume value, and the specified input volume value is stored. It is preferable to output the corresponding scaling factor and the voltage value based on that.
- magnification and voltage values can be simultaneously obtained based on a single input volume value, so that a desired combination of magnification and voltage values in the above two amplitude adjustment ranges can be easily obtained. Therefore, volume control can be easily performed within the above two amplitude adjustment ranges.
- the setting control means sets the voltage value to 0.1 times the maximum value when the amplitude is set between the intermediate value and the minimum value. Is preferred. As a result, the consumption current in the amplification means can be suppressed to about 0.1 times at the maximum, and the deterioration of the audio performance can also be suppressed to a degree that is practically inconvenient. Therefore, it is possible to provide a more sophisticated volume controller.
- the digital amplifier according to the present invention comprises any one of the above-described polyme- dium control devices, 1-bit conversion means for converting the audio signal into 1-bit signal, and the amplification means. This makes it possible to provide a digital amplifier with low power consumption and high audio performance.
- FIG. 1 is a block diagram showing the configuration of a digital amplifier according to an embodiment of the present invention.
- Fig. 2 is a graph showing the relationship between the power supply voltage of the conventional digital amplifier and the digital amplifier of Fig. 1.
- FIG. 3 is a block diagram showing the configuration of a digital amplifier according to another embodiment of the present invention.
- FIG. 4 is a graph showing control characteristics for performing volume control in the digital amplifier of FIG.
- FIG. 5 is a graph showing the change in distortion with respect to the output volume value due to the volume control of the digital amplifier of FIG. 3 and the conventional digital amplifier.
- FIG. 6 is a block diagram showing a configuration of a modification of the digital amplifier of FIG.
- FIG. 7 is a block diagram showing a digital signal recording and reproducing apparatus according to still another embodiment of the present invention.
- FIG. 8 is a block diagram showing the configuration of a conventional digital amplifier.
- FIG. 9 is a block diagram showing the configuration of another conventional digital amplifier.
- FIG. 10 is a graph showing control characteristics for performing volume control in the digital amplifier of FIG.
- Figure 1 1 is a block diagram showing the configuration of another conventional digital amplifier.
- BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples, but the present invention is not limited thereto.
- FIG. 1 is a block diagram showing the configuration of the digital amplifier 21 of the present embodiment.
- This digital amplifier 2 1 converts the analog audio signal into a 1-bit digital signal of P DM and P WM in ⁇ block 2 2, and then amplifies the power (amplitude conversion) to obtain a low-pass filter 2 3 Performs power amplification with high efficiency by converting the signal into a analog signal again by.
- the power amplification is an output transistor Q 2, Q 2 composed of an NMO SFET interposed between a high level power supply line 2 6 and a low level power supply line 2 7. It is performed in push-pull operation by the series circuit of 2 and the series circuit of the output transistors Q 23 and Q 24 consisting of NMO SFETs.
- the 1-bit signal from ⁇ ⁇ block 2 2 is input to the upper gate drive circuit 2 8, and the output transistors Q 2 1 and Q 2 3 are driven by the positive phase component and the negative phase component generated here.
- the other 1-bit signal is input to the lower gate drive circuit 29.
- the positive phase component and the negative phase component generated here drive the output transistors Q 22 and Q 24.
- the pair of NMO SFE TQ 2 1 and Q 2 4 of diagonal lines are driven in phase, and the set of output transistors Q 2 2 and Q 2 3 are driven in phase and And for output transistors Q 2 1 and Q 2 4
- the set and the set of the output transistors Q 2 2 and Q 2 3 are driven in reverse phase with each other to realize the push-pull operation.
- the upper gate drive circuit 2 8 and the lower gate drive circuit 2 9 are formed of, for example, a CMOS s gate IC.
- the upper gate drive circuit 28 receives an output voltage from a variable voltage power source 30 described later as a power source voltage, and outputs an on-time gate voltage substantially equal to the power source voltage.
- the lower gate drive circuit 29 is supplied with an output voltage from a variable voltage power supply 32 described later as a power supply voltage, and outputs an on-time gate voltage substantially equal to the power supply voltage.
- variable DC power supply voltage V 0 from the variable voltage power supply 30 is input to the drains of the output transistors Q 21 and Q 23 through the power supply line 26, and the output transistors Q 22 and Q are output.
- the source of 2 4 is brought to the GND level through the power supply line 2 7. Further, the connection point between the source of the output transistor Q21 and the drain of the output transistor Q22 and the connection point between the source of the output transistor Q23 and the drain of the output transistor Q24 become an output end. It is connected to the output end P 1 of positive phase and the output end P 2 of negative phase via low-pass filters 2 3 and 2 4 respectively.
- a load resistance R is inserted between the output terminals P 1 and P 2.
- the low pass filters 23: 24 are respectively composed of coils L 2 1 and L 2 2 and capacitors C 2 1 and C 2 2.
- variable voltage power supply 30 which is a variable power supply voltage generation means
- a PWM signal that switches between the Vcc level and the GND level is inputted from the power supply input terminal TO.
- Vcc / GND can be varied.
- the duty ratio of the WM signal is A corresponding voltage is output and input as the power supply voltage V 0 to the drain of the output transistors Q 21 and Q 23 through the power supply line 26.
- the amplitude level of the digital signal to be output is changed, and when smoothed by the low pass filters 2 3 and 2 4, the level of the analog signal to be reproduced is changed. You can adjust the volume.
- the PWM signal is a volume adjustment signal.
- the low pass filter 31 is composed of a coil L23 and a capacitor C23.
- the lower gate drive circuit 29 has a power input terminal T. While the DC power supply voltage V1 from the fixed voltage power supply (not shown) supplied to 1 is directly input, the power supply voltage V1 is added to the power supply voltage V0 in the upper gate drive circuit 28. A voltage is to be generated and input by the variable voltage power supply 32 which is drive voltage changing means. For this reason, the variable voltage power supply 32 has, similar to the variable voltage power supply 30, a low pass filter 33 consisting of a coil L 24 and a capacitor C 24, and a capacitor C 25 and a diode D. Ru.
- a PWM signal that switches between the Vcc level input to the power supply input terminal T 0 and the GND level is input to one terminal of the capacitor C 25, and the other terminal is input from the power input terminal T 1.
- Constant power supply voltage V 1 Power S input through diode D.
- the output from the other terminal of the capacitor C 25 is smoothed by the low pass filter 33 and input to the upper gate drive circuit 28. Therefore, when the PWM signal is at the GND level, the potential at one terminal of the capacitor C 25 is also at the GND level, and the potential at the other terminal becomes the power supply voltage V 1 via the diode D and the capacitor C 2. 5 is charged.
- the output voltage also changes accordingly, and the power consumption also follows it. Change.
- the gate-to-source voltage VGS 1 required to turn on the lower output transistors Q 22 and Q 24 has a source potential of the GND potential. Therefore, it is the voltage specified in the specification of the MO SFET, for example 2.5 V.
- the gate-to-source voltage VGS 2 required to turn on the upper output transistors Q 2 1 and Q 2 3 has the source potential of the power supply voltage V 0. It becomes 5 V.
- the gates of the output transistors Q 21 and Q 23 by the upper gate drive circuit 28 are The driving voltage is also increased, and when the power supply voltage V0 is lowered, the gate driving voltage is also decreased.
- the gate voltage at the on time can be always kept higher than the source voltage by a predetermined constant voltage V1.
- V l 2.5 V without affecting the switching operation of the output transistors Q 2 1 and Q 2 3
- the output gate transistor Q by the upper gate drive circuit 2 8 is The gate drive voltage of 2 1 and Q 2 3 can be set to the minimum necessary voltage, and the power consumption of the upper gate drive circuit 2 8 at the time of a small volume (the hatched portion in FIG. It is possible to reduce the difference in power consumption that results from the difference in voltage.
- the digital amplifier 21 is an analog Z digital converter which receives an analog signal, converts the analog signal into the PDM signal or the WM signal, and then amplifies the amplitude.
- the present invention is not limited to the above configuration, and the digital signal may be directly input from the outside.
- a digital noise converter may be provided externally which smoothes the output digital signals such as the low pass filters 2 3 and 2 4 to restore them into analog signals.
- the output drive circuit 25 has been described as a configuration of the H bridge having four NMOSFETs and the lower side is grounded, the upper side is grounded, the lower side is grounded. 1 ⁇ 7
- the side may be configured as a negative power supply, or NMOSFT may be configured as two half bridges.
- the drive circuit (upper gate drive circuit 28 and lower gate drive circuit 29) is switched in response to the input digital signal.
- the DC power supply is configured to be able to change its output power supply voltage
- a variable voltage power supply 32 is included that changes a drive voltage of the switching device by the drive circuit in conjunction with a change in power supply voltage of the DC power supply.
- variable voltage power supply 32 is also capable of driving the switching element such as the MOSFET gate voltage. Change it together. That is, for example, when the power supply voltage is high, the drive voltage is also high, and when the power supply voltage is low, the drive voltage is also low.
- NMO S F E T always keep the gate voltage at the ON time higher than the source voltage by a predetermined voltage.
- the drive voltage can be made the necessary minimum voltage without affecting the switching operation of the switching element, and the power consumption of the drive circuit at the time of small output amplitude can be reduced.
- the DC power supply switches a predetermined DC voltage with variable duty and smoothes the output with a low pass filter to create a variable power supply voltage to the switching element.
- the power supply 32 was switched by the DC power supply A capacitor C 2 5 whose voltage is input to one terminal, a diode D which inputs a predetermined constant voltage to the other terminal of the capacitor C 2 5, and a smoothed output from the other terminal of the capacitor C 2 5 Low-pass filter 2 4, and adds the constant voltage to the power supply voltage to the switching element to create a voltage, which is supplied as the drive voltage to the drive circuit.
- the switching output of the DC power supply when the switching output of the DC power supply is low level, for example, GND level, the potential of one terminal of the capacitor C 25 also becomes the GND level, and the other terminal of the capacitor C 25 is The potential of V becomes a constant voltage V 1 via the diode D, and the capacitor C 25 is charged.
- the switching output of the DC power supply becomes high level, for example, Vcc level, the potential of one terminal of the capacitor C 25 also becomes Vcc level, and the potential of the other terminal of the capacitor C 25 becomes Vcc. It becomes + V 1 and starts discharging.
- V 0 + V 1 is obtained, where V 0 is the changed power supply voltage from the DC power supply. That is, the power supply voltage V 0 is a potential obtained by smoothing two potentials V cc / G N D with a low pass filter, and changes according to the duty.
- FIG. 3 is a block diagram showing the configuration of the digital amplifier 11 of this embodiment.
- a digital amplifier 1 1 which is a 1-bit digital amplifier includes a digital signal source 1, a delta sigma modulation circuit 2, a gate drive circuit 3, an output full bridge circuit 4, a low pass filter (in the figure, LPF) 5, a variable voltage power supply 6 and microcomputer 7 are provided.
- LPF low pass filter
- the digital signal source 1 is a portion for inputting digital and no or analog audio signals, and has an amplitude adjustment function.
- the digital signal source 1 functions as an amplitude adjustment function by multiplying the digital signal by the multiplication factor (the digital signal) in order to adjust the amplitude of the audio signal by digital processing based on the amplitude adjustment data output from the microcomputer 7. Magnification) That is, the multiplier 1a is provided as an amplitude variable means for multiplying the amplitude adjustment data.
- the digital signal source 1 also has an A / D converter (A / D in the figure) lb that converts an analog audio signal into a digital audio signal. As a result, the digital signal source 1 outputs a digital signal from the multiplier 1a.
- the ⁇ modulation circuit 2 as 1-bit conversion means performs ⁇ modulation on the audio signal whose amplitude is adjusted by the digital signal source 1 and outputs a 1-bit digital signal (P DM signal or PWM signal) It is a circuit. Also, the ⁇ block 101 generates two series of 1-bit digital signals S 1 and S 2 of the same positive phase component based on the generated binary signal, and outputs each.
- the gate drive circuit 3 is a circuit that generates gate signals for driving the output transistors Q1 to Q4 of the output full bridge circuit 4 based on the 1-bit digital signals S1 and S2. , Have drivers 3 a, 3 b. Driver 3 a outputs a gate signal for turning on / off output transistor Q 1 based on 1-bit digital signal S 1 and an output transistor Q 3.
- the driver 3 b outputs a gate signal that turns on / off the output transistor Q 2 in reverse phase with the output transistor Q 1 based on the 1-bit digital signal S 2 and outputs the output transistor Q 4 It outputs the transistor Q 3 and the gate signal driven at the opposite phase timing.
- the drivers 3a and 3b are configured by logic circuits in order to output the correlation gate signals as described above based on the 1-bit digital signals S1 and S2.
- the output bridge circuit 4 has output transistors Q 1 to Q 4 which are N-channel M S S transistors (NMOS FET).
- the drains of the output transistors Ql and Q3 are connected to the power supply terminal 4a, and the sources of the output transistors Q2 and Q4 are connected to ground.
- the variable power supply voltage V 0 generated by the variable power supply voltage 6 is applied to the power supply terminal 4 a.
- the source of the output transistor Q1 is connected to the drain of the output transistor Q2, and the connection point is one output terminal (opposite phase output), and the source of the output transistor Q3 and the output transistor Q4 are connected.
- the drain is connected, and the connection point is the other output (positive-phase output).
- the gate signal from the above-mentioned driver 3a is input to the gate of the output transistor Ql, Q3, and the gate from the driver 3b is input to the gate of the output transistor Q2, Q4.
- a signal is input.
- the output transistors Q 1 and Q 4 are driven in phase, while the output transistors Q 2 and Q 3 are driven in phase, and the output transistors Q 1 and Q 4 and the output transistors Q 2 and Q 3 Are driven in reverse phase with each other, the output latch bridge circuit 4 performs push-pull operation, and outputs positive and negative phase pulse signals whose amplitude is amplified to V 0.
- switching amplification is performed by the gate signal (drive signal) generated by the gate drive circuit 3 based on the 1-bit digital signals S1 and S2, and the output transistor Q1 of the output full bridge circuit 4 to By driving Q 4 (switching element) to switch out the power supply voltage V 0, it is possible to output a signal in which the amplitudes of the 1-bit digital signals S 1 and S 2 are amplified. That is, in the present digital amplifier 11, the gate drive circuit 3 and the output capacitor circuit 4 described above constitute a switching amplification unit 10 (amplifying means).
- the low pass filter 5 has coils; L 1 and L 2 and capacitors C 1 and C 2.
- the positive phase pulse signal described above is input to the input end of the coil L1, and the capacitor C1 is connected between the output end and the ground.
- the pulse signal of the opposite phase is inputted to the input end of the coil L2, and the capacitor C2 is connected between the output end and the ground.
- the positive phase pulse signal is converted to an analog audio signal by passing through a low pass filter circuit consisting of a coil L 1 and a capacitor C 1
- a reverse phase pulse signal is a low pass consisting of a coil L 2 and a capacitor C 2 By passing through the filter circuit, it is converted to an analog audio signal.
- the output device 8 is an electro-acoustic transducer such as a headphone or a speaker connected to the digital amplifier 1 1, and is a load that converts the positive phase and negative phase audio from the low pass filter 5 into voice. It has 8 a.
- the positive-phase audio signal is input to one end of the load 8a, and the negative-phase audio signal is input to the other end.
- a variable voltage power supply 6 as a voltage variable means is a power supply circuit that generates a variable power supply voltage V 0 to be applied to the output full bridge circuit 4.
- This variable voltage The power supply 6 has the same servo system configuration as a general constant voltage power supply that feedbacks the output voltage and compares it with the reference voltage and controls the output voltage so that the difference disappears.
- an analog power control voltage output from the microcomputer 7 is used as a reference voltage.
- variable voltage power supply 6 outputs a single power supply voltage V 0, it is configured such that the output latch circuit 4 requires two positive and negative power supply voltages. And are configured to output two power supply voltages accordingly.
- the digital volume setting value (input volume value) from the external volume setting device 9 is input to the microcomputer 7.
- the volume setting device 9 includes, for example, an operation unit 9 a provided with an UP key and a DOWN key for volume setting by the user.
- the volume setting device 9 changes the volume setting value stepwise (predetermined volume step unit), for example, when setting the volume value with the up key and down key, press the app key once.
- the operation unit 9a may have a configuration other than the up key and down key as long as the operation input can be performed in volume step units as well, and may be independent of the volume setting unit 9 like a remote controller. It may be provided.
- the microcomputer 7 outputs the amplitude adjustment data to the digital signal source 1 and outputs the power control voltage to the variable voltage power supply 6.
- Setting control The microcomputer 7 as a means is, for each volume set value from the group setting device 9, the amplitude adjustment data and the power supply control voltage data (voltages respectively corresponding to the volume set value).
- a setting table 7a storage means in which the value adjustment table is stored in association with the value) is provided, and amplitude adjustment data and power supply control voltage data corresponding to the input volume setting value are read out from the setting table 7a.
- the microcomputer 7 also has a D / 7 A converter (D / A in the figure) 7 b for converting power supply control voltage data into the power supply control voltage of the analog port.
- the power supply control voltage data stored in the setting table 7a are set to values such as 100%, 90%,..., 10% of the power supply voltage of the microcomputer 7, for example. Also, in the setting table 7a, multiplication coefficients to be given to the multiplier 1a of the digital signal source 1 are stored as amplitude adjustment data, such as 1, 0.9: ⁇ , 0.1. .
- the output volume value (corresponding to the amplitude of the output signal from switching amplifier 10) output from output device 8 is the maximum volume value V o 1 max (corresponding to the maximum value of the amplitude) and the intermediate volume value
- V o 1 max corresponding to the maximum value of the amplitude
- the amplitude adjustment data becomes a constant value, and the power control voltage data is set to change at each volume step.
- the amplitude adjustment data is set to a value that is 100% of the amplitude value of the digital audio signal input to the multiplier 1a in the digital signal source 1, that is, "1".
- the power supply control voltage data When it is between the amplitude value V o l min (corresponding to the minimum value of the amplitude), the power supply control voltage data becomes a constant value, and the amplitude adjustment data is set to change in every volume step.
- the power supply control voltage data is set such that the power supply voltage V0 has a predetermined value lower than the maximum value (for example, the lowest value is 0.1 times the maximum power supply voltage).
- Digital audio signals if necessary, the multiplication factor from the microcomputer 7 in the multiplier 1 a to have you in the digital signal source 1 (amplitude adjustment data) amplitude is multiplied is adjusted.
- the analog audio signal is converted to a digital signal by the AZD converter 1b, and then, as with the digital audio signal, the amplitude is adjusted by multiplying the multiplication coefficient by the multiplier 1a as necessary.
- the digital signal output from the digital signal source 1 is converted into a 1-bit digital signal S 1, S 2 (positive-phase component) by the ⁇ ⁇ modulation circuit 2.
- the above 1-bit digital signals S 1 and S 2 are input to the drivers 3 a and 3 b in the gate drive circuit 3 respectively.
- the driver 3a outputs gate signals in opposite phase to each other generated based on the 1-bit digital signal S1 to the output transistors Q1 and Q3, respectively.
- the driver 3 b outputs gate signals of opposite phase generated based on the 1-bit digital signal S 2 to the output transistors Q 2 and Q 4.
- the output transistors Q 1 and Q 4 are driven in the same phase
- the output transistors Q 2 and Q 3 are driven in the same phase, and the output transistors Q 1 and Q 4 and the output transistors Q 2 and Q 3 They are driven in opposite phase to each other. This will make the output full bridge A positive-phase and reverse-phase pulse signal amplified from the circuit 4 is output.
- the combination of driving of the drivers 3a and 3b and the output transistors Q1 to Q4 is as shown in FIG. It is not limited.
- the positive phase and negative phase pulse signals are converted into an analog signal by the low pass filter 5, and the analog signal is converted into voice by the output device 8 and output.
- the volume setting value is set in the volume setting device 9.
- the microphone computer 7 performs different volume control depending on the size of this volume setting value.
- the amplitude adjustment data and the constant value are adjusted.
- Power supply control voltage data corresponding to the volume set value is read from setting table 7a.
- the amplitude adjustment data is given to the multiplier 1 a of the digital signal source 1 as a multiplication factor.
- the power supply control voltage data is converted to an analog power supply control voltage by the DZA converter 7 b and supplied to the variable voltage power supply 6.
- the digital signal input to the digital signal source 1 is multiplied by the above multiplication coefficient ("1") by the multiplier la, and the digital signal is output as it is with the input amplitude. Further, the variable voltage power supply 6 outputs a power supply voltage V0 controlled to be the above power supply control voltage.
- the pulse signal amplified to the value of the above-mentioned power supply voltage V 0 is output. Therefore, the audio of the volume according to the power supply voltage V 0 is output from the output device 8.
- the input calendar (indicated by ⁇ in the figure) (the level of the digital signal input from the digital signal source 1 to the ⁇ modulation circuit 2) is constant. Since the power supply voltage V 0 shown by is variable, the output level from the output full bridge circuit 4 changes substantially in accordance with the power supply voltage V 0 and changes in the unit of the program step, as shown in FIG. That is, in the volume range A, the value of the power supply voltage V 0 determines (adjusts) the output volume value.
- the power supply voltage V 0 decreases as the output volume value is adjusted from the maximum volume value V o 1 max to an intermediate volume value V o 1 mid. Current consumption is also reduced accordingly.
- the power control voltage data of a fixed value may be output.
- Amplitude adjustment data of a value according to the volume setting value is read out from the setting table 7a.
- the amplitude adjustment data is given to the multiplier 1 a of the digital signal source 1 as a multiplication factor.
- the power supply control voltage data of a fixed value is converted to the power supply control voltage of the analog by the DZA converter 7 b and given to the variable voltage power supply 6.
- the input digital audio signal is subjected to amplitude adjustment by being multiplied by a multiplication coefficient according to the output volume value in the multiplier 1a.
- variable voltage power supply 6 outputs a constant power supply voltage V 0 controlled to be the above power supply control voltage.
- the output full bridge circuit 4 outputs an amplified pulse signal within a range not exceeding a predetermined power supply voltage V 0. Therefore, from the output device 8, speech of a voice according to the amplitude level adjusted by the multiplier 1a is outputted.
- volume range B in volume range B, the input feedback indicated by ⁇ in the figure is variable, and power supply voltage V 0 shown in ⁇ in the figure is constant, so the output full bridge circuit 4 As shown in the figure below, the output level from ⁇ ⁇ changes at the same change rate as the incoming call level in units of volume steps. That is, in the volume range B, the output volume value is determined (adjusted) by the value of the multiplication factor.
- the power supply control voltage data is set so that the power supply voltage V 0 is a predetermined value lower than the maximum value, so the output volume value is an intermediate volume value V o 1 mid If adjusted to approach the minimum volume value V o 1 min from, the current consumption does not change.
- the power supply voltage V 0 to the output full bridge circuit 4 is fixed at a predetermined level, the servo gain is secured by the variable voltage power supply 6 as in the low voltage output, and By stabilizing, the power supply voltage V 0 can be stably output. This can improve audio performance such as distortion, S / N and residual noise in the output full bridge circuit 4.
- the deterioration of the distortion factor can be suppressed as compared with the configuration of the prior art in which the power supply voltage is variable in the entire volume range.
- the distortion factor changes in the volume range B at almost the same change rate as the change rate in the volume range A. , It worsens with the decrease of output volume value.
- the distortion factor is significantly reduced in the volume range B compared to the distortion factor of the prior art.
- the consumption current in output full bridge circuit 4 can be maximized at 0. It can be suppressed to about 1 time, and the deterioration of audio performance can also be suppressed to a level that is practically inconvenient. If the above lower limit value is further lowered, power consumption can be further reduced, but it is not preferable because the audio performance is deteriorated so as to cause practical inconvenience (the sound quality is deteriorated).
- the digital amplifier 1 1 of the present embodiment uses the digital signal source 1 to the ⁇ modulation circuit 2 with a constant multiplication coefficient in the range (volume range A) where the output volume value is large.
- the power supply voltage V 0 of the output full multiplier circuit 4 is made variable while fixing the amplitude of the input digital signal input to the input, while the power supply voltage V 0 is within the small range (volume range B) of the output volume value.
- the volume control by the microcomputer 7 is performed so as to make the amplitude of the input digital signal variable while keeping it constant.
- the microcomputer 7 is provided with the setting table 7a in which the amplitude adjustment data and the data of the power supply control voltage respectively corresponding to the poly set values from the volume setting device 9 are stored in association with each other. Set the amplitude adjustment data and power supply control voltage data corresponding to the volume setting value. Read from 1 bull 7 a. This allows different data to be obtained simultaneously based on a single volume setpoint, thus facilitating the desired combination of amplitude adjustment data and power supply control voltage data as described above in the two volume ranges. Can be obtained. Therefore, the volume can be easily controlled in the two volume range as described above.
- V o 1 mid priority is given to reduction of power consumption, reduction of audio performance, or both, depending on the performance of the 1-bit digital amplifier required. It is set arbitrarily depending on the combination.
- the digital amplifier 12 is configured in the same manner as the digital amplifier 1 1 except for the variable voltage power supply 6, and a DC / DC converter 1 3 instead of the variable voltage power supply 6 and the embodiment described above.
- a variable voltage power supply 3 2 in one digital amplifier 1 is provided.
- D C / D C converter 1 3 is DZ in microcomputer 7
- the DC / DC converter 13 includes a power supply circuit 1 3 a, a WM circuit 1 3 b, and a variable voltage power supply 3 0 in the digital amplifier 2 1 of the first embodiment described above.
- the power supply circuit 1 3 a is a circuit similar to the variable voltage power supply 6 described above, and outputs a power supply voltage V 0 controlled based on the power supply control voltage.
- the WM circuit 13 b is constituted by, for example, a general PWM comparator for generating a PWM signal, and an oscillator provided in the PWM circuit 13 b or an externally supplied constant cycle and Triangular wave signal with constant amplitude and above.
- the power supply voltage V 0 is compared, and a pulse signal having a duty ratio proportional to the level of the power supply voltage V 0 is output as a result of the comparison.
- variable voltage power supply 30 demodulates the power supply voltage V 0 at a level proportional to the duty ratio of the P w M signal by smoothing the p w M signal from the P WM circuit 13 b with the low pass filter 31. Further, the variable power supply voltage 30 is connected to the variable voltage power supply 3 2 in the same manner as the variable voltage power supply 3 0 in the digital amplifier 21 of the first embodiment.
- Power supply voltage V 0 output from variable voltage power supply 30 is applied to power supply terminal 4 a of output full bridge circuit 4.
- the DC power supply voltage V I is supplied to the driver 3 b of the gate drive circuit 3 as a power supply voltage as it is, in addition to being input to the variable voltage power supply 32.
- the voltage V 0 + V 1 output from the variable voltage power supply 32 is given as a power supply voltage to the driver 3 a of the gate drive circuit 3.
- the digital amplifier 12 configured in this way suppresses the power consumption of the output full page circuit 4 in the range where the output volume value is large, while the output volume In the lower range, deterioration of audio performance can be suppressed.
- the digital amplifier 2 1 when the power supply voltage V 0 is high, the gate drive voltage of the output transistors Q 1 and Q 3 by the driver 3 a is also increased, and when the power supply voltage V 0 is lowered. The gate drive voltage is also lowered, and the on-time gate voltage can always be maintained higher than the source voltage by a predetermined voltage V 1 which is predetermined.
- driver 3 a without affecting the switching operation of output transistors Q 1 and Q 3.
- FIG. 7 is a block diagram showing a mini-disc apparatus as a digital signal recording and reproducing apparatus according to this embodiment.
- a disc 41 which is a rewritable magneto-optical recording medium, is used.
- Addresses assigned as recording units are assigned consecutive numbers across the entire recording surface of the disc 41 and are set in advance.
- a group of related information data Audio data such as music, which is a data set, is recorded on the recording surface.
- the disc 4 1 has a read-only area for reproduction only and a U-T0C area that can be rewritten on the circumference part immediately thereafter (list information). And its U—a program area for recording audio data and subdata outside the TOC area. And, the lead-out area is sequentially set in the outermost part.
- an optical pickup 42 for reproducing audio data from the recording surface of the disc 4 1 is provided, and the optical pickup 42 is also used to record new audio data on the disc 4 1.
- a memory controller a shock proof memory controller
- a voice decompression 'compression circuit 4 7, a D / A' A / D converter 4 8, a system controller (control means) 4 9 such as a microcomputer, and a servo circuit 5 0 are provided.
- the driver circuit 51 the spin motor 52, the feed motor 53, the power ON / OFF circuit 54, the head drive unit 55, and the recording head 56
- An audio output terminal 5 7, an audio input terminal 5 8, an input unit 5 9, and a digital amplifier 6 0 are provided.
- a song rewriting key 5 9 a for instructing rewriting of a recorded song to a new song and a song number for designating a song to be rewritten are specified in the input unit 5 9, and a song for instructing rewriting of all songs Designated numeric keypad ⁇ All songs specification numeric keypad (instruction section) 5 9 b and control key 5 9 c are provided for writing.
- the controller key 5 9 c is for instructing a general function, that is, a recording / reproducing function as a recording / reproducing apparatus such as recording / reproducing, etc.
- a general function that is, a recording / reproducing function as a recording / reproducing apparatus such as recording / reproducing, etc.
- the recording key, pause Includes keys, play key, and stop key are examples of the recording key, pause Includes keys, play key, and stop key.
- the digital amplifier 60 is configured by the digital amplifier 2 1 shown in FIG. 1, the digital amplifier 1 1 shown in FIG. 3 or the digital amplifier 1 2 shown in FIG.
- the analog audio signal output to the audio output terminal 57 is converted to a 1-bit digital signal to perform amplification with high efficiency.
- the digital amplifier 60 composed of the digital amplifier 11 can also convert the multi-bit digital audio signal output from the audio compression / decompression circuit 47 directly into a 1-bit digital signal. .
- the disc motor 41 When reproducing the disc 41 in the mini disc apparatus, the disc motor 41 is rotationally driven by the spin motor 52 driven by the driver circuit 51, and the feed motor 53 driven by the driver circuit 51.
- the pickup 2 is sent in the radial direction of the disk 41, and the audio data recorded on the disk 41 is read by the pickup 42.
- the audio data read out by the pickup 4 2 is amplified by the RF amplifier 4 3 and sent to the encoder / decoder signal processing circuit 4 c .
- the RF amplifier 4 3 is an audio signal read out by the pickup 4 2
- the servo control signal such as the focus error signal and the tracking error signal is generated from the data and output to the servo circuit 50.
- the servo circuit 50 applies the servo control of the pickup 4 2 with the servo control signal from the RF amplifier 4 3 and the control signal from the system controller 4 9 comprising a microphone computer etc. To control the driver circuit 51 as described above. Further, the driver circuit 51 drives the pickup 42, the feed motor 53 and the spin motor 52 in accordance with the control signal from the servo circuit 50.
- the encoder / decoder signal processing circuit 4 4 demodulates the signal amplified by the amplifier 4 3, further performs signal processing such as error correction, and performs memory control.
- Signal processing such as error correction
- the memory controller 45 writes the signal sent from the encoder 'decoder signal processing circuit 44 as a writing means to the shock proof memory 46 as a storage means. Also, the memory controller 45 reads out the audio data stored in the shock proof memory 46 as a memory reading means, and sends it to the audio expansion / compression circuit 47.
- the audio expansion / compression circuit 4 7 decompresses and restores the input audio data in accordance with a predetermined format in the built-in audio expansion circuit, and sends it to the D / A ⁇ A / D converter 4 8.
- D / A ⁇ A / D converter 4 8 converts the input digital signal into a built-in D / A converter 4 8 a and converts it into an audio signal. Then, the audio signal is output from the output terminal 57 as audio.
- the audio signal input from the audio input terminal 5 8 is sent to the DZA ⁇ AZD converter 4 8, and the audio signal which is an analog signal is incorporated into the audio data which is a digital signal.
- the converter 48b converts it and the audio data is sent to the audio expansion / compression circuit 47.
- Voice decompression 'Compression circuit 4 7 is a built-in voice compression circuit that reduces the amount of input data to about 1/5 by the information compression technology of a mini disk unit called ATRAC (Adaptive TRansf orm Acoustic Coding).
- ATRAC Adaptive TRansf orm Acoustic Coding
- data compression the compressed audio data is sent to the memory controller 5, the memory controller 4 5 writes the audio data sent to the shock-proof memory 4 6.
- the memory controller 45 also reads out the audio data stored in the shock proof memory 46 and sends it to the encoder / decoder signal processing circuit 44 where it is used for modulation and error correction. Add the code etc.
- Such voice data is sent to the head driver 5.5.
- the head driver 55 outputs a digital signal to the recording head 56 based on the audio data, and the above recording head based on the control signal from the system controller 49.
- the strong laser beam from the pickup 4 2 is controlled by the system controller 4 9 via the power supply ON / OFF circuit 54 and the driver circuit 5 1.
- the digital signal recording and reproducing apparatus according to the third embodiment is a portable device, it is necessary to drive the apparatus with limited power for a long time, and the technology for reducing power consumption described in the first and second embodiments. Is particularly effective.
- the present invention since the present invention adopts a configuration for reducing the power at the time of small volume in the digital amplifier, it can contribute to the reduction of the power consumption if applied to a digital audio reproducing apparatus etc. is there. Furthermore, the present invention is configured to reduce distortion in a range where the output volume value is small. It is useful to improve audio performance if it is applied to digital audio playback devices etc.
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Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/500,276 US7049885B2 (en) | 2002-07-29 | 2003-07-25 | Volume adjustment device, digital amplifier, and digital signal reproducing device |
AU2003252703A AU2003252703A1 (en) | 2002-07-29 | 2003-07-25 | Volume adjustment device, digital amplifier, and digital signal reproducing device |
EP03784486A EP1544996B1 (en) | 2002-07-29 | 2003-07-25 | Volume adjustment device, digital amplifier, and digital signal reproducing device |
JP2004527316A JP4143605B2 (ja) | 2002-07-29 | 2003-07-25 | デジタルアンプおよびデジタル信号再生装置 |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002-220208 | 2002-07-29 | ||
JP2002220208 | 2002-07-29 | ||
JP2003072288 | 2003-03-17 | ||
JP2003-72288 | 2003-03-17 |
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WO2004015855A1 true WO2004015855A1 (ja) | 2004-02-19 |
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PCT/JP2003/009504 WO2004015855A1 (ja) | 2002-07-29 | 2003-07-25 | ボリューム調整装置、デジタルアンプおよびデジタル信号再生装置 |
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US (1) | US7049885B2 (ja) |
EP (1) | EP1544996B1 (ja) |
JP (1) | JP4143605B2 (ja) |
AU (1) | AU2003252703A1 (ja) |
WO (1) | WO2004015855A1 (ja) |
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EP1517438A1 (en) * | 2003-09-19 | 2005-03-23 | Sony Corporation | Digital amplifier |
JP2006180199A (ja) * | 2004-12-22 | 2006-07-06 | Alpine Electronics Inc | デジタルアンプ搭載装置 |
JP2006237859A (ja) * | 2005-02-23 | 2006-09-07 | Rohm Co Ltd | D級アンプ、それを用いた信号増幅回路ならびに電子機器 |
EP1865597A1 (en) * | 2005-03-28 | 2007-12-12 | NEC Corporation | Amplifier apparatus |
JP2009278508A (ja) * | 2008-05-16 | 2009-11-26 | Sharp Corp | 音声出力装置及び音声出力方法 |
US8680916B2 (en) | 2004-08-25 | 2014-03-25 | Nujira Limited | High efficiency variable voltage supply |
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CN1638266A (zh) * | 2003-12-16 | 2005-07-13 | 国际整流器公司 | 利用可调供电电压的d类放大器中的音量控制 |
KR100595652B1 (ko) * | 2004-02-12 | 2006-07-03 | 엘지전자 주식회사 | 이동 통신 단말기의 송신 전력 제어 장치 및 방법 |
GB2414120B (en) | 2004-05-11 | 2008-04-02 | Splashpower Ltd | Controlling inductive power transfer systems |
JP4568572B2 (ja) * | 2004-10-07 | 2010-10-27 | ローム株式会社 | 音声信号出力回路、および音声出力を発生する電子機器 |
US7126416B2 (en) * | 2004-11-17 | 2006-10-24 | Princeton Technology Corporation | Pulse amplitude modulation (PAM) method and circuit for improving the performance of a D-class audio amplifier |
US20090274321A1 (en) * | 2008-04-30 | 2009-11-05 | Lear Corporation | Audio amplifier and technique for power efficiency thereof |
US8134420B2 (en) * | 2009-03-30 | 2012-03-13 | Brother Kogyo Kabushiki Kaisha | Communication apparatus and signal processing method thereof |
JP5327481B2 (ja) * | 2011-01-13 | 2013-10-30 | オンキヨー株式会社 | トーンコントロール装置 |
JP5510564B2 (ja) | 2012-05-25 | 2014-06-04 | 日本電気株式会社 | スイッチングアンプおよびそれを用いた送信機 |
US9918172B1 (en) * | 2016-08-19 | 2018-03-13 | Semiconductor Components Industries, Llc | Active output driver supply compensation for noise reduction |
US10509624B2 (en) * | 2017-01-30 | 2019-12-17 | Cirrus Logic, Inc. | Single-bit volume control |
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Also Published As
Publication number | Publication date |
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JP4143605B2 (ja) | 2008-09-03 |
US20050122162A1 (en) | 2005-06-09 |
AU2003252703A1 (en) | 2004-02-25 |
EP1544996A4 (en) | 2006-05-17 |
EP1544996A1 (en) | 2005-06-22 |
EP1544996B1 (en) | 2011-06-29 |
JPWO2004015855A1 (ja) | 2005-12-02 |
US7049885B2 (en) | 2006-05-23 |
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