WO2004019487A1 - デジタル増幅装置 - Google Patents
デジタル増幅装置 Download PDFInfo
- Publication number
- WO2004019487A1 WO2004019487A1 PCT/JP2003/009442 JP0309442W WO2004019487A1 WO 2004019487 A1 WO2004019487 A1 WO 2004019487A1 JP 0309442 W JP0309442 W JP 0309442W WO 2004019487 A1 WO2004019487 A1 WO 2004019487A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- digital
- signal
- pass filter
- feedback circuit
- terminal
- Prior art date
Links
Classifications
-
- 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
- H03F2200/331—Sigma delta modulation being used in an amplifying circuit
Definitions
- the present invention relates to reducing distortion of a digital amplifying device, and more particularly to a digital amplifying device used in a cardio.
- FIG. 6 shows a circuit block diagram of a conventional digital amplifier.
- the ⁇ modulator (denoted by ⁇ in Fig. 6) 101 converts the input analog input signal 105 into a pulse signal that has been subjected to pulse density modulation.
- the constant voltage switch (denoted as SW in FIG. 6) 102 is composed of a switch element having a small on-resistance such as an M ⁇ SFET, and power-amplifies the output signal of the ⁇ modulator 101.
- Low-pass filter (shown as LPF in Fig. 6) 103 is composed of a coil and a capacitor. The cut-off frequency of the low-pass filter 103 is set to a frequency lower than the switching frequency of the constant voltage switch 102.
- the switching component included in the output signal of the constant voltage switch 102 is attenuated, and the power output of the constant voltage switch 102 is smoothed and restored to an analog output signal.
- the feedback circuit (denoted by 3 in FIG. 6) 104 feeds back the output of the low-pass filter 103 to the input of the ⁇ modulator 101.
- a means for detecting the output current is effective.
- the output voltage is proportional to the output current, so it is possible to detect the output voltage and reduce the coil distortion accurately.
- the output current may be greatly distorted even if the output voltage is not distorted, and it is difficult to correct this distortion by detecting the output voltage.
- a digital amplifying section having a differential input terminal for inputting an analog signal and a differential output terminal for outputting a digital signal, converting the analog signal into a digital signal, amplifying power, and outputting a digital signal,
- a current feedback circuit is provided to feed back a signal related to the signal obtained by transformer coupling with the low-pass filter to the differential input terminal.
- FIG. 1 is a circuit block diagram of a digital amplifier according to Embodiment 1 of the present invention.
- FIG. 2 is a transfer characteristic diagram of the first current feedback circuit of the digital amplifier according to the first embodiment of the present invention.
- FIG. 3 is a characteristic diagram of the total harmonic distortion with respect to the output power of the digital amplifier according to the first embodiment of the present invention.
- FIG. 4 is an external view of a first transformer-coupled coil of the digital amplifying device according to the second embodiment of the present invention.
- FIG. 5 is a circuit block diagram of a digital amplifier according to Embodiment 3 of the present invention.
- FIG. 6 is a circuit block diagram of a conventional digital amplifier. BEST MODE FOR CARRYING OUT THE INVENTION
- the present invention provides a digital amplifier that solves the above-mentioned problems of the conventional digital amplifier.
- embodiments of the present invention will be described with reference to the drawings.
- FIG. 1 is a circuit block diagram of a digital amplifier according to Embodiment 1 of the present invention.
- the analog input terminal 11 is connected to the differential input terminal 20 of the digital amplifier 13 through an input impedance element 12 (denoted by Z in FIG. 1).
- the differential output terminal 21 of the digital amplifier 13 is connected to the load output terminal 22 through the low-pass filter 14.
- the low-pass filter 14 includes a first transformer-coupled coil 15, a capacitor 16 connected between the first transformer-coupled coil 15 and the load output terminal 22, and a load output terminal 22. It consists of a bypass capacitor 17 connected to the ground.
- the primary coil of the first transformer-coupled coil 15 is inserted in series between the differential output terminal 21 and the load output terminal 22.
- the secondary coil of the first transformer-coupled coil 15 has one terminal connected to ground and the other terminal differentially connected through the first current feedback circuit (shown as / 3 C in Figure 1) 18 Connect to input terminal 20.
- the differential output terminal 21 is also connected to the differential input terminal 20 through a voltage feedback circuit (denoted as jSV in FIG. 1) 19.
- jSV voltage feedback circuit
- the audio analog input signal applied to the analog input terminal 11 is input to the differential input terminal 20 of the digital amplifier 13 through a pair of input impedance elements 12.
- This analog signal is converted to a digital signal PWM signal (pulse width modulation signal) that is sufficiently higher than the frequency of the analog audio signal by the digital amplifier 13 and power-amplified.
- the power-amplified PWM signal is input from the differential output terminal 21 to the low pass filter 14.
- the PWM signal is integrated by the low-pass filter 14, output to the speaker 33 through the load output terminal 22, and To be played.
- the digital signal output from the differential output terminal 21 of the digital amplifier 13 is fed back to the differential input terminal 20 through the voltage feedback circuit 19.
- current is fed back from the secondary coil of the first transformer-coupled coil 15, which is a component of the low-pass filter 14, to the differential input terminal 20 through the first current feedback circuit 18.
- FIG. 2 shows a transfer characteristic diagram of the first current feedback circuit 18.
- a curve 23 represents a voltage characteristic induced in the secondary coil of the first transformer-coupled coil 15 having a slope of the coupling coefficient M
- a curve 24 represents a voltage characteristic of the first current feedback circuit 18. 6 shows transfer characteristics.
- the first current feedback pack circuit 18 attenuates the switching frequency component as distortion by setting the cut-off frequency Fc of the current feedback circuit 18 lower than the switching frequency Fs of the PWM signal. It is necessary to let them. Further, it is necessary to adjust the loop gain and the phase of the current feedback circuit 18 so as to cancel the distortion component of the signal frequency Ft.
- the third-order distortion generated in the first transformer-coupling coil 15 is the largest, and the transfer characteristics of the current feedback circuit 18 can be adjusted so that only this third-order distortion is fed back. Third-order distortion can be greatly reduced.
- the feedback gain may be the reciprocal of the gain A of the digital amplifier 13, that is, 1 ZA.
- FIG. 3 shows a characteristic diagram of the total harmonic distortion with respect to the output power of the digital amplifier according to the first embodiment of the present invention.
- the horizontal axis is the output power, and the vertical axis is all It represents the harmonic distortion factor (denoted as THD + N in Fig. 3).
- the polygonal line 25 indicates the characteristic in the case where the first current feedback circuit 18 is not provided, and the polygonal line 26 indicates the characteristic in the case where the first current feedback circuit 18 is provided.
- the output power is about 2 to 30 W in the range of 1 to 30 W compared to the conventional digital amplifier. Improvement of 0 dB or more was confirmed.
- FIG. 3 shows the case where the frequency F of the analog input signal is 50 Hz, the output load RL of the digital amplifier is 1 ⁇ , and the power supply voltage Vcc for driving the digital amplifier is 14.4 V. 3 shows an example of the characteristic.
- the distortion of the low-pass filter could be reduced by the current feedback circuit that detects and returns the current distortion that caused the distortion.
- FIG. 4 is an external view of the first transformer-coupled coil 15 in the digital amplifier according to the second embodiment of the present invention.
- Figure 4 shows the first transformer-coupled coil composed of a toroidal double winding.
- the resistance component of the first transformer-coupled coil 15 causes a loss, and thus needs to be reduced. Since this resistance component is proportional to the number of turns of the coil winding, it is necessary to obtain a desired inductance with a small number of turns. Therefore, it is desirable to use a core material having high magnetic permeability.
- the number of turns of the primary winding 28 is set so as to obtain the inductance of the mouth-to-pass filter 14. In order to reduce the resistance component, it is desirable to use a thick winding as long as a predetermined number of turns can be obtained.
- the secondary winding 29 may be formed by using a thin winding. The number of windings can be determined almost arbitrarily by a balance with the transfer characteristic of the first current feedback circuit 18, but it is preferable that the number of windings be several times or more so that the coupling coefficient M is stabilized. Also, by fixing the winding with an adhesive or the like, the stability of the coupling coefficient M can be obtained.
- FIG. 5 shows a circuit block diagram of a digital amplifying device according to Embodiment 3 of the present invention.
- the description will focus on the parts that are different from the first embodiment.
- the second transformer-coupling coil 30 is a component of a line filter for power input, and its primary coil forms an inductance component of the line filter, and its resistance component is preferably small.
- the secondary coil, which is electromagnetically coupled to the primary coil, is composed of two coils, which are wound with almost the same number of turns and opposite polarities, and one end of which is connected to the ground.
- the capacitor 31 forms a capacitance component of the line filter, and is connected to the output side of the primary coil of the second transformer-coupling coil 30. It is desirable that the capacitance value of the capacitor 31 be set sufficiently large in order to supply a current with little fluctuation to the digital amplifier 13.
- a pair of second current feedback circuits (denoted as / 3 1 in FIG. 5) 3 2 are connected to terminals of the second transformer coupled coil 30 that are not connected to the ground of the secondary coil. . Further, the polarity and the gain of the second current feedback circuit 32 are set so as to cancel the ripple voltage of the power and source circuits. As a component of the second current feedback circuit 32, a resistor alone can be used to adjust the gain only. It may be a low-pass filter with a low frequency.
- the power supply line supplied from the power supply input terminal 34 to the digital amplification section 13 has a small but some impedance, so that a ripple current is generated in the power supply line. Since this power supply is the reference voltage of the digital amplifying unit 13, the ripple current directly becomes the output component. Therefore, the second transformer-coupling coil 30 detects the distortion current, and considers this as a ripple current of the power supply and adds it to the input signal. At this time, the correction amount is adjusted by the second current feedback circuit 32, and as a result, the distortion component due to the ripple current of the power supply can be canceled in the output voltage from the digital amplifier 13.
- the ripple current of the power supply can be detected as the distortion current without increasing the impedance of the power supply line, and this is fed back. As a result, distortion due to the impedance of the power supply line can be reduced.
- the digital amplifying device of the present invention includes the first current feedback circuit that detects and feeds back the current distortion that causes the distortion.
- the distortion of the mouth-pass filter can be reduced.
- the digital amplifying device of the present invention includes a voltage feed-back circuit that feeds back a digital signal from the differential output terminal to the differential input terminal, so that both the current and the voltage can be fed back. Furthermore, the distortion of the low-pass fill can be reduced.
- the digital amplifying device of the present invention can be put to practical use with almost no change from the original configuration of the digital amplifying device by including a single-pass filter including a toroidal double winding and a capacitor. Therefore, current detection can be performed at low cost, and distortion can be reduced at low cost.
- the digital amplifier of the present invention can reduce the distortion of the low-pass filter by the first current feedback circuit that detects and returns the current distortion that causes the distortion, and the power supply circuit can be reduced by the second current feedback circuit. Distortion due to impedance can also be reduced.
- the digital amplifying device of the present invention is a digital amplifying device provided with a current feedback circuit that transduces a current to a differential input terminal by transducing with a low-pass filter, and detects current distortion that causes distortion.
- the feedback of the current feedback circuit reduces the distortion of the single pass filter.
- the digital amplifier by this invention can reduce the distortion of a single pass filter by carrying out current feedback. Further, the digital amplifying device according to the present invention, Distortion due to the impedance of the power supply circuit can be reduced by the current feedback from the power supply circuit.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/504,214 US7202742B2 (en) | 2002-08-22 | 2003-07-25 | Digital amplification device |
EP03792637A EP1455445B1 (en) | 2002-08-22 | 2003-07-25 | Digital amplification device |
DE60302330T DE60302330T2 (de) | 2002-08-22 | 2003-07-25 | Digitale verstärkungseinrichtung |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002241425A JP3956800B2 (ja) | 2002-08-22 | 2002-08-22 | デジタル増幅装置 |
JP2002-241425 | 2002-08-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2004019487A1 true WO2004019487A1 (ja) | 2004-03-04 |
Family
ID=31943992
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2003/009442 WO2004019487A1 (ja) | 2002-08-22 | 2003-07-25 | デジタル増幅装置 |
Country Status (5)
Country | Link |
---|---|
US (1) | US7202742B2 (ja) |
EP (1) | EP1455445B1 (ja) |
JP (1) | JP3956800B2 (ja) |
DE (1) | DE60302330T2 (ja) |
WO (1) | WO2004019487A1 (ja) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7720457B2 (en) * | 2006-10-19 | 2010-05-18 | Motorola, Inc. | Method and apparatus for minimizing noise on a power supply line of a mobile radio |
KR100829112B1 (ko) * | 2006-12-04 | 2008-05-16 | 삼성전자주식회사 | 휴대 단말기의 오디오 신호 왜곡 보상 장치 및 방법 |
EP2109867A4 (en) * | 2007-01-11 | 2014-12-24 | Keyeye Comm | BROADBAND planar transformers |
US8224009B2 (en) | 2007-03-02 | 2012-07-17 | Bose Corporation | Audio system with synthesized positive impedance |
JP4978409B2 (ja) * | 2007-10-03 | 2012-07-18 | パナソニック株式会社 | デジタル増幅装置 |
JP6269423B2 (ja) * | 2014-09-30 | 2018-01-31 | 株式会社Jvcケンウッド | 電力増幅装置および電力増幅方法 |
JP6229628B2 (ja) * | 2014-09-30 | 2017-11-15 | 株式会社Jvcケンウッド | 電力増幅装置および電力増幅方法 |
TWI716797B (zh) * | 2019-01-04 | 2021-01-21 | 周重甫 | 動態阻抗調節音頻放大器架構及方法 |
US10749486B2 (en) * | 2019-01-11 | 2020-08-18 | Bose Corporation | Class D amplifier current feedback |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62144411A (ja) * | 1985-12-19 | 1987-06-27 | Hitachi Shonan Denshi Kk | 電力増幅回路 |
JPH04159803A (ja) * | 1990-10-23 | 1992-06-03 | Matsushita Electric Ind Co Ltd | 電力増幅器 |
JPH07131272A (ja) * | 1993-10-29 | 1995-05-19 | N F Kairo Sekkei Block:Kk | 電力増幅装置 |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4092610A (en) * | 1977-02-17 | 1978-05-30 | Raytheon Company | Modulated carrier amplifying system |
US5410592A (en) * | 1993-06-04 | 1995-04-25 | Harris Corporation | Class `D` audio speaker amplifier circuit with state variable feedback control |
US5721490A (en) * | 1995-02-09 | 1998-02-24 | Hitachi Medical Corporation | Power source apparatus including a plurality of output current amplifiers connected in parallel and MRI apparatus using the same |
NL1011002C2 (nl) | 1999-01-12 | 2000-07-20 | Univ Eindhoven Tech | Versterkerschakeling. |
JP3549042B2 (ja) | 1999-04-21 | 2004-08-04 | シャープ株式会社 | Δς変調を用いるスイッチング増幅器 |
US6476674B2 (en) * | 2001-01-24 | 2002-11-05 | Momentum Data Systems | Method and apparatus for error correction of amplifier |
US6563377B2 (en) * | 2001-10-09 | 2003-05-13 | Evenstar, Inc. | Class D switching audio amplifier |
-
2002
- 2002-08-22 JP JP2002241425A patent/JP3956800B2/ja not_active Expired - Fee Related
-
2003
- 2003-07-25 US US10/504,214 patent/US7202742B2/en not_active Expired - Fee Related
- 2003-07-25 DE DE60302330T patent/DE60302330T2/de not_active Expired - Lifetime
- 2003-07-25 EP EP03792637A patent/EP1455445B1/en not_active Expired - Fee Related
- 2003-07-25 WO PCT/JP2003/009442 patent/WO2004019487A1/ja active IP Right Grant
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62144411A (ja) * | 1985-12-19 | 1987-06-27 | Hitachi Shonan Denshi Kk | 電力増幅回路 |
JPH04159803A (ja) * | 1990-10-23 | 1992-06-03 | Matsushita Electric Ind Co Ltd | 電力増幅器 |
JPH07131272A (ja) * | 1993-10-29 | 1995-05-19 | N F Kairo Sekkei Block:Kk | 電力増幅装置 |
Non-Patent Citations (1)
Title |
---|
See also references of EP1455445A4 * |
Also Published As
Publication number | Publication date |
---|---|
JP2004080661A (ja) | 2004-03-11 |
JP3956800B2 (ja) | 2007-08-08 |
DE60302330T2 (de) | 2006-08-03 |
EP1455445A4 (en) | 2005-03-23 |
EP1455445B1 (en) | 2005-11-16 |
EP1455445A1 (en) | 2004-09-08 |
US7202742B2 (en) | 2007-04-10 |
DE60302330D1 (de) | 2005-12-22 |
US20050113055A1 (en) | 2005-05-26 |
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