• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Power amplifier for amplifying an electrical input signal in a frequency operating range and providing an output signal, comprising a switching means (22), filter means (14, 16) for generating a power output signal through-pass filtering of the square signal, input signal means for receiving the superelectric signal and of it to a first input of the switching means, the power amplifier also comprising a feedback circuit (24) for feedback of the output signal to the first input of the switching means. The power amplifier comprises a servo amplifier (32) connected to receive an error signal appearing on the first input of the switching means and to direct a corrective output signal to a second input of the switching means (22) to neutralize the effect of the error signal on the output signal. The invention relates to a method of amplifying an electrical input signal in a working frequency range. The method comprises the measures of recording an error signal occurring at the first input of the switching means, amplifying the error signal in the operating frequency range, inverting the error signal and transmitting the amplified and inverted error signal to a second input of the switching means. AH p4293se00 ps se 11-01-03 ver. 14
    公开号:SE0950670A1
    申请号:SE0950670
    申请日:2009-09-14
    公开日:2011-03-15
    发明作者:Patrik Bostroem
    申请人:Patrik Bostroem；
    IPC主号:
    专利说明:

    15 20 25 30 2 band. Typically, a Class D amplifier includes a second order low pass filter with a relatively high Q value for demodulating the PWM pulses. This filter shifts the phase asymptotically to -180 ° and the higher the Q value, the earlier it reaches -180 °. When the filter is loaded, the Q value decreases.
    The actual pulse width modulation can be accomplished in various ways. The most obvious way is to use a reference signal, for example a triangular wave signal, and then compare the input signal or setting value with this reference signal. Each time these signals intersect, the output stage changes state. A disadvantage of this reference signal technology is that the average value of the pulse train corresponds to the set value only as long as the supply voltages are constant and the state change is infinitely fast.
    In addition, of course, the triangular wave must be ideal.
    The reference signal technology has no feedback at all, which means that there is a lack of control of the demodulation filter. There are in fact two signal paths, one from the input to the output and one from the supply to the outputs. The channel separation and supply voltage suppression becomes very poor. An individual advantage is that the switching frequency is constant.
    Forward-coupled supply can be used to reduce the dependence on the supply voltage.
    The use of a digital device such as a DSP for calculating the pulse width instead of comparing the setting value with the triangular wave gives basically the same result. However, there are several possibilities to compensate for non-ideal features of components. A DSP solution is also more complicated and expensive.
    A very effective way to achieve pulse width modulation is through self-oscillation. A comparator is used to compare the average value of the pulse train with the setting value and if the error is negative, the positive switch is switched on and vice versa if it is positive. The operating frequency is close to the frequency where the feedback has -180 ° phase shift. Some solutions use the demodulation filter to produce the averaging and this allows the amplifier to adjust errors that occur during and after the demodulation filter.
    AH p4293se00 ps se 11-01-03 ver. 14 10 15 20 25 30 3 Without additional circuits, the switching frequency would be equal to the resonant frequency of the filter, which is usually around 50kHz and this is not acceptable. A zero and zero negative pressure resistor are inserted into the sensing circuit to push up the frequency for about a decade. This zero increases the amplitude of the modulation signal and reduces the loop gain and thus increases the nonlinearities. The result of this post-filter self-oscillation topology is therefore that the linear distortion (the distortion that does not add any new frequency content such as amplitude and phase) is very low to be a class D amplifier, but the non-linear distortion is worse. An early description of self-oscillating Class D amplifiers was made by Clayton Sturgeon of Texas, who filed a 1976 patent application with the number US 4,041,411.
    A later prior art document is WO3 / 090343, which shows and describes a power amplifier for amplifying an electrical signal in a frequency operating range, comprising switching means for generating a square signal by alternately coupling the square signal to a first supply voltage and a second supply voltage. filter means for generating a power output signal by low-pass filtering of the square signal, input signal means for receiving the electrical signal and driving the switching means and a control circuit connected to the power signal output and the input signal means for controlling the power amplifier.
    Another possibility is to add a second-order active integrator that demodulates the pulse train and provides a very high loop gain at low frequencies. The switching frequency is thus completely controlled by this integrator and not at all by the Q value of the output filter. The function of this self-oscillating topology with prefilter is therefore very robust and simple, and it provides very low non-linear distortion, especially at low frequencies.
    In a self-oscillating topology with a pre-filter, however, the linear distortion becomes high, ie. the frequency response and the phase are completely load dependent and a desired response curve can only be achieved with specific load impedance. The switching frequency of all self-oscillating topologies varies with the modulation depth (pulse width). This is advantageous in terms of efficiency, since the switching losses become lower when the line losses increase, but if external AH p4293se00 ps see 11-01-03 ver. 14 10 15 20 25 30 4 rather a loop is added to increase the loop gain, there is a risk that this loop captures the switching frequency, whereby the amplifier would end up in a destructive undertone oscillation mode.
    There is a need to increase the loop gain to reduce the non-linear and linear distortion of self-oscillating Class D amplifiers. This is usually done by including an integrator that integrates the difference between the output signal and the input signal, and thus creates an error signal, to further increase the loop gain in the audio band. At least one problem arises here. At start-up, before the class D stage is in operation, or when cutting the output signal, the integrator will be supplied with a large error signal, which will be integrated until the integrator becomes saturated, after which the fault will continue to charge an integrating capacitor. This causes the integrator to hang.
    Consequently, there is a need to eliminate this hanging behavior in order to be able to use an integrator in combination with a class D step.
    SUMMARY OF THE INVENTION In accordance with the invention, the disadvantages and problems of amplifiers in the prior art are eliminated by providing a self-oscillating Class D amplifier with lower distortion, without affecting its frequency response. This is accomplished by adding a circuit that measures the error at the negative input of a modulating / switching power stage of the Class D amplifier and which then affects a positive input (a reference to the modulating stage) to minimize the error. This type of amplifier will have a very low linear distortion compared to other class D amplifiers.
    Another advantage is that the frequency response of the class D stage is not affected by fault amplifier pure.
    The frequency response has a large fire width and the output impedance is low. By adding a fault servo amplifier, the non-linear distortion can be significantly reduced. In some embodiments, the servo amplifier includes an integrator that measures the error of the negative input of the modulator, amplifier AH p4293se00 ps see 11-01-03 ver. 14 10 15 20 25 30 5 ker it in the audio area, inverts it and leads it to the positive input of the modulator (modulator reference input).
    To make the amplifier behave well during cutting and during start-up, the integrator can be equipped with a latch to limit the integrating signal. The latch circuit can be connected via a capacitor included in the integrator. In some embodiments, the latch includes two zener diodes that convert the integrator to a voltage follower, if the voltage across the integrating capacitor exceeds the zener voltage plus 0.7 V in one direction. There are also other ways to realize the latch.
    A practical embodiment of the invention was compared with a standard globally modulated class D step with respect to frequency response and phase change. In a standard class D step, the gain point is -3dB at 235 kHz and the absolute phase change at 20 kHz is -8 degrees.
    An embodiment in accordance with the invention with a fault servo amplifier added has the point for -3dB at 230 kHz and -10 degrees phase change at 20 kHz. Consequently, the frequency response is in principle unchanged compared with a class D step in itself. This result can be obtained with a servo amplifier, or error amplifier, which measures an error in a modulation node and corrects it by supplying it to a reference input of the modulator.
    BRIEF DESCRIPTION OF THE DRAWINGS In order to clarify how the above and other advantages and objects of the invention are achieved, a more specific description of the above invention will be made by reference to certain embodiments thereof, as set forth in the accompanying drawings.
    It should be noted that these drawings only show typical embodiments of the invention and therefore should not be construed as limiting its scope. The invention is described and explained with further specification and details with reference to the accompanying drawings, in which: Fig. 1 is a general block diagram of a previously known class D amplifier, AH p4293se0O ps see 11-01-03 ver. Fig. 2 is a schematic block diagram of a basic embodiment of an amplifier in accordance with the invention, Fig. 3 is a schematic circuit diagram of an embodiment of an amplifier in accordance with the invention, and Fig. 4 is a overview block diagram of an alternative design of a limiting circuit.
    THE INVENTION In the prior art amplifier shown in Fig. 1, a non-inverting input of an integrator circuit 10 receives an electrical input signal. An output of the integrator circuit 10 is connected to a switching means 12.
    A power output from the switching means 10 is connected to a low-pass filter, comprising an inductor 14 and a capacitor 16. From the inductance 14 a local feedback loop 18 is connected to an inverting input of the switching means 13. A non-inverting input of the switching means 13 is connected to an output of the integrator circuit 10. An external feedback loop 20 connects the inductor 14 to an inverting second input of the integrator circuit 10. Under clipping conditions, the integrator will hang, leading to a high proportion of audible artifacts. A possible improvement would be to keep the supply voltage at a lower level to limit how much the integrator hangs, but this does not solve the problems during start-up or in current limiting situations.
    In the embodiment of an amplifier in accordance with the invention shown in Fig. 2, an output of a comparator 22 acting as a switching means is connected to a signal output OUT via an inductor 14 in a conventional manner. A signal input IN is connected to an inverting input of the comparator via a resistor R6 and through a further resistor R3. The inverting input of the comparator is a modulation node of the amplifier. A feedback loop 24 is provided between the signal output and the inverting input of the comparator. The signal appearing on the inverting input of the comparator can be defined as an error signal. In the embodiment shown, the feedback loop comprises feedback capacitor 26 in series with a feedback resistor 28. A parallel-connected resistor 30 AH p4293se0O ps see 11-01-03 ver. 14 10 15 20 25 30 7 is also included in the feedback loop 24. In the embodiment shown, an inductor 14 is arranged between the output of the comparator 22 and the signal output OUT.
    In the amplifier previously known in Fig. 1, the external feedback loop is used to compare the output signal with the input signal. In accordance with the invention, a servo amplifier 32, or an error amplifier, is connected to measure the error signal appearing on the modulation node of the comparator. The error signal is then amplified in the audio area and inverted to create a corrective output signal. The corrective output signal is routed to a non-inverting input of the comparator, which usually constitutes the modulator reference. This causes the error signal to be neutralized.
    As shown in Fig. 2, the modulation node is connected to the servo amplifier 32 and more particularly to an inverting input of an integrator 34, which forms part of an integrating circuit 10. The integrating circuit 10 comprises one between an output of the integrator 34 and the inverting input of the integrator 34 is connected to the integrating capacitor 36. The output of the integrator 34 is connected to the non-inverting input of the comparator 22 via a line resistor R50. The non-inverting input of the comparator is also connected to ground via a resistor R45.
    The embodiment shown in Fig. 2 also comprises a latch circuit 40 which improves the characteristics of the amplifier during cutting and under starting conditions.
    The latch circuit comprises a first zener diode 37 and a second zener diode 38 which are connected in series and in opposite directions across the integrating capacitor 36. The two zener diodes 37, 38 make the integrator circuit a voltage follower, if the voltage across the integrating capacitor exceeds them - the down voltage plus 0.7 V in either direction. There are also other ways to realize the latch.
    A simulation model of a self-oscillating Class D amplifier stage equipped with a subsequent filter with a fault servo amplifier for increasing the loop gain in the audio area is shown in Fig. 3. Only the components that have essential properties are listed below.
    AH p4293se0O ps se 11-01-03 ver. 14 10 15 20 8 A first switch S1 switches on at 0.001V and switches off at OV.
    A second switch S2 has inverse switch-on and switch-off values. The switches S1 and S2 are connected to a first voltage source 42 and a second voltage source 44, respectively. The voltage sources 42 and 44 provide the required or available voltage, which in the embodiment shown is 5OV. S1 and S2 together form the switching means 22 based on a comparator and a power stage. A resistor R44 and a capacitor C19 roughly correspond to the running time of the comparator switching stage (which is actually there).
    The output signal from the switching means 22 is passed through the inductor 14 and is received in a load RL.
    The amplifier circuit AR1 forms the integrator circuit 10, in which a capacitor C21 acts as a pole. In the embodiment shown, AR1 has +/- 15V as the supply voltage. A capacitor C14 and a resistor R35 push away the switching frequency from the filter resonant frequency and up to a desired much higher frequency.
    The components used in the embodiment shown in Fig. 3 are shown in the table below.
    Comp. Value Comp. Value R3 2 kOhm R50 2 kOhm R6 2 kOhm C1 1 pF R10 8.2 kOhm C14 130 pF R35 1.1 kOhm C19 20 nF R44 10 Ohm C21 1.2 nF R45 6 kOhm L1 8 pH R46 2 kOhm A more ideal limiter or latch 40 is shown in Fig. 4. A first transistor Q1 will be activated or conducted when an output of the integrator 34 falls below 0.7V. Thereby, the output signal of the integrator will be fed back to the inverting input of the integrator 34 through the first transistor Q1 and a first diode D1. Correspondingly, the second transistor AH p4293se00 ps will see 11-01-03 ver. 14 10 15 9 Q2 to be activated or lead, when an output of the integrator 34 rises to a value above 0.7V.
    Transistors Q1 and Q2 are conventional transistors and diodes D1 and D2 are conventional diodes. Resistors R8 and R9 are used to reverse the diodes when transistors Q1 and Q2 are not conducting. The output signal from the integrator is routed to the comparator 22, as described above.
    It is to be understood that although descriptive embodiments of the invention have been specifically included, various modifications will be apparent to one skilled in the art without departing from the scope and spirit of the invention. Accordingly, it is not intended that the scope of the appended claims be limited to the description set forth herein, but that the claims be construed as including such equivalent solutions as will be apparent to one skilled in the art to which the invention pertains.
    AH p4293se0O ps se 11-01-03 ver. 14
    权利要求:
    Claims (10)
    [1]
    A power amplifier for amplifying an electrical input signal in a frequency operating range and providing an output signal, comprising a switching means (22) for generating a square signal by alternately conducting the square signal to a first supply voltage and a second supply voltage, filter means (14, 16) for generating a power output signal by low-pass filtering of the square signal, input signal means for receiving the electrical signal and transmitting it to a first input of the switching means, the power amplifier also comprising a feedback circuit (24) for coupling of the output signal to the first input of the switching means, characterized by a servo amplifier (32) connected to receive an error signal appearing on the first input of the switching means and to conduct a corrective output signal to a second input of the switching means (22) to neutralize the effect of the error signal on the output signal.
    [2]
    A power amplifier according to claim 1, wherein the servo amplifier (32) has a amplifying first input connected to the first input of the switching means (22) and an output connected to a second input of the switching means (22) and wherein the servo amplifier (32) is designed to amplify the error signal and invert it, before it is led to the second input of the switching means (22).
    [3]
    A power amplifier according to claim 1, wherein the servo amplifier (32) comprises an integrator (34, AR1) having a non-inverting input, an inverting input and an integrator output, and an integrating interconnected between the integrator output and the inverting input capacitor (36).
    [4]
    A power amplifier according to claim 3, wherein a latch (40) is arranged to limit one to the integrating output of the integrator (34; AR1). AH p4293se00 ps se 11-01-03 ver. 14 10 15 20 25 30 11
    [5]
    A power amplifier according to claim 4, wherein the latch circuit (40) comprises a first zener diode (37) and a second zener diode (38), the zener diodes being connected in series in opposite directions across the integrating capacitor (36).
    [6]
    A power amplifier according to claim 3, wherein the integrator output of the integrator (34; AR1) is connected to the second input of the switching means (22) via a line resistor (R50), the second input being a non-inverting input.
    [7]
    A power amplifier according to claim 1, wherein the first input of the switching means is an inverting input.
    [8]
    A power amplifier according to claim 1, wherein its operating frequency range is an audio frequency band.
    [9]
    A power amplifier according to claim 1, wherein the switching means (12) comprises a first switch (S1) and a second switch (S2), the first switch (S1) connecting a first voltage source (42) and the second switch (S2). ) connects a second voltage source (44) to generate an output signal.
    [10]
    Method for amplifying an electrical input signal in a working frequency range and providing an output signal by generating a square signal by alternately connecting the square signal to a first voltage source and to a second voltage source, low-pass filtering the square signal and performing an internal feedback of the output signal first input of a switching means, there are signs of the measures of recording an error signal appearing at the first input of the switching means, amplifying the error signal in the operating frequency range, inverting the error signal and AH p4293se00 ps see 11-01-03 ver. Transmitting the amplified and inverted error signal to a second input of the switching means. AH p4293se00 ps se 11-01-03 ver. 14
    类似技术:
    公开号 | 公开日 | 专利标题
    SE0950670A1|2011-03-15|Power Amplifier
    KR100435182B1|2004-06-09|Digital pwm input d class amplifier by pwm negative feedback
    KR100760024B1|2007-09-20|Gate control circuit with soft start/stop function
    US7944297B2|2011-05-17|Class D amplifier
    US5200711A|1993-04-06|Pulse-width modulated, linear audio-power amplifier
    JP6452622B2|2019-01-16|Envelope tracking modulator with feedback
    US10090813B2|2018-10-02|Power amplifier
    US8604710B2|2013-12-10|Multi-mode dimming circuit
    US7675362B2|2010-03-09|Switching amplifier
    JP2009060466A|2009-03-19|Class-d amplifier
    US9287826B2|2016-03-15|Sine-cosine modulator
    CN105103318A|2015-11-25|Circuit assembly and method for controlling a piezoelectric transformer
    SE0950295A1|2010-10-31|Power Amplifier
    CN206117481U|2017-04-19|Negative feedback circuit
    TWI407688B|2013-09-01|Pwm modulator for a class-d amplifier and class-d amplifier adaptive to analog and digital input by using the same
    WO2017041354A1|2017-03-16|Pulse width modulation circuit
    US10819293B2|2020-10-27|Power amplifier
    CN213754451U|2021-07-20|Class D amplifier with filter circuit
    CN102594144A|2012-07-18|Current control type direct current voltage reduction circuit and power consumption reduction method thereof
    CN213754445U|2021-07-20|Class D amplifier with protection circuit
    TWI565231B|2017-01-01|Power limiting amplifier
    TW201334402A|2013-08-16|PWM modulator for a class-D amplifier and class-D amplifier adaptive to analog and digital input by using the same
    WO2006109245A1|2006-10-19|Class-d amplifier
    同族专利:
    公开号 | 公开日
    WO2011031213A2|2011-03-17|
    EP2478635A2|2012-07-25|
    US20120235742A1|2012-09-20|
    CN102714488B|2015-04-29|
    US8736367B2|2014-05-27|
    CN102714488A|2012-10-03|
    SE534502C2|2011-09-13|
    ES2428515T3|2013-11-08|
    EP2478635B1|2013-07-31|
    WO2011031213A3|2011-05-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    NL7511161A|1974-09-24|1976-03-26|Clayton L Sturgeon|METHOD AND DEVICE FOR AMPLIFYING AN ELECTRICAL SIGNAL.|
    US5805020A|1996-06-27|1998-09-08|Harris Corporation|Silent start class D amplifier|
    EP0932932B1|1997-08-12|2003-10-01|Koninklijke Philips Electronics N.V.|Device for amplifying digital signals|
    JP2005523631A|2002-04-19|2005-08-04|コーニンクレッカ　フィリップス　エレクトロニクス　エヌ　ヴィ|Power amplifier|
    US6924700B2|2002-10-03|2005-08-02|Mitsubishi Denki Kabushiki Kaisha|Class D amplifier|
    US7038535B2|2003-03-29|2006-05-02|Wai Laing Lee|PWM digital amplifier with high-order loop filter|
    KR100498497B1|2003-05-10|2005-07-01|삼성전자주식회사|Class-D power amplifier providing for removing excessive response phenomenon in returning to steady state from abnormal state and method thereof|
    US7157969B2|2004-02-27|2007-01-02|Bhc Consulting Pty., Ltd.|Low distortion class D amplifier using a controlled delay|
    US20090072902A1|2004-10-27|2009-03-19|Extraordinary Technology Pty Ltd|Low distortion class-d amplifier|
    JP2006174585A|2004-12-15|2006-06-29|Sanyo Electric Co Ltd|Feedback circuit|
    WO2006109245A1|2005-04-15|2006-10-19|Koninklijke Philips Electronics N.V.|Class-d amplifier|
    KR20090045337A|2006-08-15|2009-05-07|엔엑스피 비 브이|Electronic device for self oscillating class d system|
    EP1993203A1|2007-05-18|2008-11-19|Stmicroelectronics SA|Overdrive control system|
    US7863841B2|2007-06-15|2011-01-04|Paolo Menegoli|Class H drive|US10164581B2|2014-12-08|2018-12-25|Icepower A/S|Self-oscillating amplifier with high order loop filter|
    US9503023B2|2015-04-01|2016-11-22|Nxp B.V.|Class-D amplifier|
    EP3360249B1|2015-10-05|2019-08-14|Telefonaktiebolaget LM Ericsson |Amplification device incorporating limiting|
    WO2019110154A1|2017-12-07|2019-06-13|Purifi Aps|An amplifier with a compensator with a network of at least third order|
    EP3721552A1|2017-12-07|2020-10-14|Purifi ApS|Amplifier circuit|
    WO2019110153A1|2017-12-07|2019-06-13|Purifi Aps|An amplifier with an at least second order filter in the control loop|
    US11159126B2|2019-02-17|2021-10-26|University Of Southern California|Sub-harmonic switching power amplifier|
    法律状态:
    2016-05-03| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    SE0950670A|SE534502C2|2009-09-14|2009-09-14|Power Amplifier|SE0950670A| SE534502C2|2009-09-14|2009-09-14|Power Amplifier|
    ES10771828T| ES2428515T3|2009-09-14|2010-09-08|Power amplifier|
    CN201080050274.1A| CN102714488B|2009-09-14|2010-09-08|Power amplifier|
    EP10771828.0A| EP2478635B1|2009-09-14|2010-09-08|Power amplifier|
    PCT/SE2010/050953| WO2011031213A2|2009-09-14|2010-09-08|Power amplifier|
    US13/395,680| US8736367B2|2009-09-14|2010-09-08|Power amplifier with switching means and feedback circuit|
    [返回顶部]