High-performance audio amplifier

Abstract

The invention relates to a high-performance audio amplifier (102) intended to control at least one loudspeaker (R44), the amplifier comprising a preamplification stage (301) receiving an input signal (S1), a power amplification stage (302) connected to the preamplification stage (301) and a feedback delivering an image of an output signal (3) to the preamplification stage (301), the power amplification stage (302) comprising two power supply circuits (155a, 155b) including MOSFET transistors (M1, M2). The invention is characterized in that it comprises a sub-circuit for assisting in charging, a sub-circuit for assisting in discharging and a voltage shift sub-circuit for the MOSFET transistors (M1, M2).

Description

Technical Field

[0001] The present invention relates to the field of amplifiers. The present invention particularly relates to a high-power audio amplifier intended to control at least one loudspeaker.

[0002] High-power amplifiers have specific applications when providing sound in recording studios or concert halls. They are particularly used to power electro-dynamic loudspeakers.

[0003] The present invention advantageously makes it possible to obtain a high-power audio amplifier having better efficiency than prior art amplifiers while guaranteeing low distortion.

Background Art

[0004] Conventionally, a high-power amplifier includes at least one active component, such as a transistor or a tube, that makes it possible to amplify the power of the signal received as input while maintaining the shape of the input signal.

[0005] The circuit of a high-power amplifier generally includes a preamplification stage, followed by a power amplification stage. More precisely, the output of the power amplification stage is fed back to the preamplification stage, and the preamplification stage detects, for example by means of a differential pair, the difference between the output signal and the input signal over time. This difference detected in the preamplification stage is then amplified in the power amplification stage to form an output signal, which is conventionally transmitted to at least one loudspeaker.

[0006] Thus, by way of example, FIG. 1 illustrates a high-power amplifier 100, the input signal of which is applied at point S1. The output of the high-power amplifier 100 powers a loudspeaker, which is represented by a resistor R44 connected between point 3 and ground.

[0007] The diagram of the high-power amplifier 100 is symmetric. It also includes an upper part 140a and a lower part 140b. The upper part 140a amplifies the positive half-wave of the input signal S1, and the lower part 140b amplifies the negative half-wave of the input signal S1.

[0008] In the example of FIG. 1, the high-power amplifier 100 is powered by a single voltage level of + / - 65V.

[0009] The preamplification stage 201 includes two differential pairs 110a, 110b, and the two differential pairs 110a, 110b each include two transistors Q1, Q2 and Q3, Q4 assembled by mirroring each other. Accordingly, the emitters of the transistors Q1, Q2 are connected to the -65V power bus via resistors R2, R3 and the first constant current source I, while the emitters of the transistors Q3, Q4 are connected to the +65V power bus via resistors R4, R5 and the second current source I of the same value.

[0010] The collectors of the transistors Q2, Q4 are connected to the +65V and -65V power buses respectively, while the collectors of the transistors Q1, Q3 are connected to the +65V and -65V power buses via resistors R1, R11 respectively. In the absence of feedback, the gain of the preamplification stage 201 depends on the resistor ratios R1 / R2 and R11 / R4.

[0011] The bases of the transistors Q1 and Q3, and the bases of the transistors Q2 and Q4 are connected to each other. Also, the bases of the transistors Q1 and Q3 are powered by the input signal S1. The bases of the transistors Q2 and Q4 are connected to the loudspeaker R44 via the resistor R18 and are configured to form the feedback applied to the preamplification stage. The collectors of the transistors Q1 and Q3 ensure the connection between the preamplification stage 201 and the power amplification stage 202.

[0012] The power amplification stage 202 includes two transistors Q8 and Q9, and the two transistors Q8 and Q9 are connected to the preamplification stage 201 via resistors R23 and R57 by their respective bases. Also, a voltage source T1 is installed between resistor R23 and resistor R57 and is adapted to bias transistors Q8 and Q9 in class AB. This voltage source T1 makes it possible to supply a voltage equal to the sum of the voltages necessary to turn on transistors Q8 and Q9.

[0013] Also, transistors Q8 and Q9 are respectively connected to the +65V and -65V power buses by their collectors. The emitters of transistors Q8 and Q9 are connected to the loudspeaker R44 via resistors R16 and R17. These resistors R16 and R17 are added to control the quiescent current (i.e., the value of the current conducted by the amplifier when it does not receive an input signal). Without these resistors R16 and R17, the quiescent current would depend on the characteristics and temperature of transistors Q8 and Q9, which is prohibited.

[0014] In addition, the circuit in FIG. 1 has particularities at the bases of transistors Q2 and Q4. In fact, the latter are connected to a protection line 403, and the protection line 403 includes a resistor R28 assembled in series with a capacitor C4 connected to ground. This assembly is a voltage divider, and the voltage at point S2 is equal to the voltage of the output signal 3 in AC multiplied by R28 / (R18 + R28). In fact, capacitor C4 behaves like a short circuit when the voltage flowing through the circuit is alternating. On the other hand, capacitor C4 behaves like an open circuit when the voltage flowing through the circuit is DC. In this case, the output signal 3 of the high-power amplifier 100 is directly connected to point S2. The voltage gain of the high-power amplifier 100 then becomes equal to 1, which makes it possible to limit the undesirable DC component that may occur above the voltage applied to the terminals of the loudspeaker R44.

[0015] In this type of amplifier, the voltage measured with respect to ground at point S1 and the voltage measured with respect to ground at point S2 are equal. In other words, the gain of the high-power amplifier 100 is equal to the ratio of the values of the resistors (R18 + R28) / R28.

[0016] Therefore, FIG. 1 illustrates a high-power voltage amplifier. Also, as shown in FIG. 2, there is another category (high-power current amplifier).

[0017] This category of high-power current amplifier 101 has the same topology as that for the high-power voltage amplifier 100, i.e., it has a pre-amplification stage 201 connected to the amplification stage 203.

[0018] Unlike the high-voltage amplifier 100 of FIG. 1, the current measurement resistor R6 is inserted between the loudspeaker R44 and ground. Further, the current amplifier 101 does not have a protection line 403. The bases of the transistors Q2 and Q4 are connected to an interconnection point P1 located between the resistor R6 and the loudspeaker R44.

[0019] In this configuration, the image of the current applied at point S2 in FIG. 3 thus intersects the loudspeaker R44. As a result, the transconductance (i.e., the ratio between the output current passing through the loudspeaker R44 and the input voltage applied at point S1 of the amplifier 101) is equal to 1 / R6 A / V. For a loudspeaker having an impedance Z, the voltage gain is Z / R6.

[0020] Therefore, the voltage or current amplification assemblies are similar, especially with respect to the pre-amplification stage and the power amplification stage. They differ only with respect to the loudspeaker connection and feedback.

[0021] In the following prior art, other classes of amplifiers will be described with reference to voltage amplifiers, but the present invention is not limited to this type of amplifier.

[0022] The class system can be used to characterize different high-power amplifier topologies. The class system assigns letters based on the relationship between the shape of the input signal and the shape of the output signal, and based on the duration for which the active component is used during the amplification of the input signal.

[0023] Among existing amplifier classes, class A amplifiers have a topology such that the active component conducts a current approximately 50% higher than the maximum output current in the absence of an input signal. This is called the quiescent current. In modulation, the quiescent current is superimposed on the output current. This type of amplifier can provide excellent sound quality, but it has the disadvantage of generating significant heat dissipation. Therefore, the energy efficiency of this class of amplifier (defined by the ratio between the effective output power and the absorbed power) is approximately 10%.

[0024] Class B amplifiers are characterized by a topology such that the active component conducts for more than 50% of the input signal period when a sinusoidal input signal is applied as the input. For this class of amplifier, the quiescent current is zero. The efficiency of this type of amplifier is higher than that of class A amplifiers, but the distortion characteristics of the output signal are significantly degraded compared to class A amplifiers. Therefore, class B amplifiers produce a lower quality sound. Nowadays, it is extremely rare for manufacturers to use this class of amplifier.

[0025] Class AB amplifiers feature a topology where the active components conduct for more than 100% of the input signal period, but with a quiescent current that is approximately 1% of the maximum output current. This type of amplifier has higher energy efficiency than Class A amplifiers, typically in the range of 30% to 50%, but has lower sound quality. Thus, Class AB amplifiers represent a good compromise between performance and energy efficiency.

[0026] Regarding Class D amplifiers, a technique is used where the active components operate like switches. The signal is then converted by pulse-width modulation. This system increases the energy efficiency to approximately 70%. On the other hand, the output signal contains more noise and distortion, and it is difficult to reproduce high frequencies with this class of amplifier.

[0027] Class G amplifiers have several power buses and can switch from one to another according to the power output requirements. This makes it possible to increase the energy efficiency by reducing the power dissipated in the active components.

[0028] Class H amplifiers use power buses, and the supply voltage of those power buses "follows" or is modulated by the input signal. Typically, they have two power buses, similar to those of Class G, but only the highest supply voltage is modulated. The modulated power supply is generally realized using a Class D amplifier.

[0029] The subject of the present invention relates particularly to these last two categories of amplifiers.

[0030] Figure 3 illustrates the upper part of the power amplification stage 204. The latter is connected to the power supply circuit 150. Naturally, this power amplification stage also includes a lower part (not shown) that mirrors the upper part with an equivalent power supply circuit. Similarly, the circuit also includes a preamplification stage, which is connected to, for example, an independent power supply or a powerful power bus, and it is also connected to the power supply circuit 150.

[0031] The power supply circuit 150 enables the selection of the power level of the power amplification stage 204 that is adapted to the amplification power requirement. Thus, when the amplification voltage is greater than the threshold, the first powerful power bus must be used, while when the amplification voltage is lower than this threshold, the second weaker power bus can be used. The use scenario of the lower power bus improves the overall efficiency of the amplifier compared to class A, B, and AB amplifiers.

[0032] Furthermore, the power supply circuit 150 has a structure independent of the preamplification stage 201 and the power amplification stage 204. In the example of Figure 3, the power amplification stage 204 includes the transistor Q10, and the base of the transistor Q10 is connected to the emitter of the transistor Q8. This so-called "Darlington" configuration enables an increase in the current gain. The emitters of the transistors Q8 and Q10 are connected to the loudspeaker R44 by their respective resistors R16 and R19. They have, for example, their respective quiescent currents, which are equal to 6 mA for the transistor Q8 and 75 mA for the transistor Q10.

[0033] The power amplification stage 204 is connected to the power supply circuit 150 at the collectors of transistors Q8 and Q10. This power supply circuit 150 is connected to two voltage buses having individual levels V+ and V++. Thus, the power supply circuit 150 enables selection of one or the other of these voltage levels in response to an amplification requirement. Typically, the first power bus delivers 65V and the second power bus delivers 35V. The second power bus is intended to be used to power the power amplification stage 204 when the output signal to be generated does not have a very high voltage (typically, less than 32V).

[0034] Due to the relatively low current passing through transistor Q8 (typically, less than 10% of the current passing through transistor Q10), the collector of transistor Q8 can be directly connected to the first power bus V++, which does not cause significant additional power dissipation. This embodiment makes it possible to improve the stability of the amplifier, and the operation as a current amplifier tends to be weakened.

[0035] To select an appropriate voltage level, the MOSFET transistor M1 is directly connected to the first power bus V++ by its drain and is connected to the second power bus V+ via the fourth diode D3 by its source. The MOSFET transistor M1 typically switches with respect to a threshold of 27V and then operates linearly beyond this threshold. It passes the first power bus V++ when a control voltage greater than the threshold is applied thereto. This voltage is controlled by the association of the first diodes D8, D10 (which are connected between the gate of the MOSFET transistor M1 and the loudspeaker R44) and the second resistors R8, R27 (which are connected between the drain and the gate of the MOSFET transistor M1).

[0036] Diode D15 is connected between the collector of transistor Q10 and loudspeaker R44, and the cathode of the diode is connected to the collector of transistor Q10.

[0037] The different signals obtained by this assembly are illustrated in Figure 4.

[0038] Therefore, the signal numbered 1 in Figures 3 and 4 represents the gate signal of MOSFET transistor M1. The output signal numbered 3 in Figures 3 and 4 represents the output signal of the amplifier, that is, the signal at the terminals of loudspeaker R44. The output signal numbered 2 in Figures 3 and 4 represents the output signal of power supply circuit 150. Therefore, we notice that output signal 3 is distorted. In fact, the peaks of the sine curve are flattened, and the shift occurs near 27 μs. This saturation of output signal 3 is explained by the fact that the supply voltage of MOSFET transistor M1 is insufficient for the amplifier to deliver the output voltage correctly.

[0039] Similarly, signal 2 has an abnormal voltage peak corresponding to an overvoltage at the gate of MOSFET transistor M1 between 40 μs and 47 μs. This leads to power loss and deterioration of the amplifier efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0040] Therefore, the technical problem proposed to be solved by the present invention is to obtain a high-output audio amplifier that enables limiting the distortion identified on the signal, and thus improving the efficiency of the amplifier and reducing saturation.

Means for Solving the Problems

[0041] To solve this problem, the present invention proposes a power supply circuit including a sub-circuit for assisting charging, a sub-circuit for assisting discharging, and a MOSFET transistor controlled by a voltage shift sub-circuit, which enables obtaining better efficiency of the amplifier while limiting saturation and distortion of the amplifier output signal.

[0042] In other words, the present invention is a high-power audio amplifier intended to control at least one loudspeaker, - a pre-amplification stage for receiving an input signal, - a power amplification stage, the power amplification stage being connected to the pre-amplification stage and providing an output signal intended to supply power to the at least one loudspeaker, and the pre-amplification stage and the power amplification stage having mirror-mounted upper and lower parts, the power amplification stage; - feedback for providing an image of the output signal to the pre-amplification stage, - an upper power supply circuit, the upper power supply circuit being connected to the upper part of the power amplification stage and enabling it to be powered by a first or second power bus, the upper power supply circuit; - a lower power supply circuit, the lower power supply circuit being connected to the lower part of the power amplification stage and enabling it to be powered by a first or second power bus, the lower power supply circuit and - Each power supply circuit includes a MOSFET transistor and monitoring means, the MOSFET transistor is controlled by the monitoring means and is adapted to perform switching between one or the other of two power buses, the MOSFET transistor is connected to the second power bus via a fourth diode, the first terminal of the fourth diode is connected to the source of the MOSFET transistor, and the drain of the MOSFET transistor is connected to the first power bus. Regarding a high-power audio amplifier.

[0043] The present invention is such that each power supply circuit - A sub-circuit for assisting in charging the MOSFET transistor, the sub-circuit for assisting in charging includes at least a first resistor, the first terminal of the first resistor is connected to the gate of the MOSFET transistor, and the second terminal of the first resistor is connected to an interconnection point. A sub-circuit for assisting in charging, - A sub-circuit for assisting in discharging the MOSFET transistor, the sub-circuit for assisting in discharging includes at least a second and a third resistor and a bipolar transistor, the base of the bipolar transistor is connected to the first terminal of the third resistor, its emitter is connected to the gate of the MOSFET transistor, its collector is connected to the source of the MOSFET transistor via the second resistor, and the second terminal of the third resistor is connected to an interconnection point. A sub-circuit for assisting in discharging, - A voltage shift sub-circuit, the voltage shift sub-circuit includes a first diode mounted in parallel with a first capacitor, the first terminal of the first diode and the first terminal of the first capacitor are connected to a first interconnection node, and the second terminal of the first diode and the second terminal of the first capacitor are connected to a second interconnection node. A voltage shift sub-circuit It is further characterized by including.

[0044] In particular, the sub - circuit for assisting charging enables the MOSFET transistor to charge more quickly. In fact, it first includes a first resistor which preferably has a high value of resistance (i.e., approximately 15 kΩ) so as not to exchange too much energy with the output of the amplifier and not to generate more distortion. This first resistor allows only a low current to flow to charge or discharge the gate of the MOSFET transistor. The gate behaves like a capacitor, but the combination of the MOSFET transistor and the first resistor increases the duration of the charging time and the discharging time.

[0045] The sub - circuit for assisting discharging enables the MOSFET transistor to discharge more quickly. The bipolar transistor, in particular, enables the gate of the MOSFET transistor to discharge when the sinusoidal input signal is in its decreasing phase.

[0046] The voltage - shift sub - circuit ensures that the gate potential of the MOSFET transistor is always higher than the amplifier output. Typically, the gate potential of the MOSFET transistor can be 15 V higher than that of the amplifier output. Also, the voltage - shift sub - circuit compensates for the voltage drop in the MOSFET transistor.

[0047] According to a second embodiment, the voltage - shift sub - circuit further includes at least a fourth resistor and a second diode mounted in parallel. The first terminal of the second diode and the terminal of the fourth resistor are connected to a first interconnection node, and the second terminal of the fourth resistor and the second terminal of the second diode are connected to a third interconnection node.

[0048] The addition of these components makes it possible to reduce the distortion observed on the amplifier output signal. This improvement in distortion is effective for a sinusoidal input signal that has a relatively low frequency (i.e., approximately 1 kHz).

[0049] Advantageously, according to a third embodiment, the sub-circuit for assisting charging further includes a fifth resistor, the fifth resistor being mounted in series with the third diode, and the fifth resistor and the third diode being mounted in parallel with a branch of the sub-circuit for assisting charging that includes the first resistor.

[0050] The third diode (which is mounted in parallel with the first resistor) allows the current intended to charge the gate of the MOSFET transistor to flow and blocks the current intended to discharge the gate of the MOSFET transistor. The fifth resistor preferably has a low value (i.e., approximately 300 Ω). This fifth resistor makes it possible to charge the gate of the MOSFET transistor more quickly. The reason is that the charging time constant is equal to the product of the resistance and the capacitance.

[0051] The addition of these components here, again, makes it possible to improve the distortion for a sinusoidal input signal up to a frequency of 20 kHz. Thus, the distortion is improved across the entire frequency spectrum. Accordingly, the acoustic reproduction of the loudspeaker connected to the amplifier of the present invention is improved. The listener perceives less distortion compared to the prior art amplifier.

[0052] According to the fourth embodiment, the voltage shift sub-circuit further includes a second capacitor and a third capacitor. The second capacitor is mounted in parallel with the first capacitor and the first diode, and the third capacitor is mounted in parallel with the third diode and the fifth resistor. These additional components make it possible to limit the noise (i.e., the interference signal superimposed on the expected output signal).

[0053] In fact, each power supply circuit includes a first protection diode. The first terminal of the first protection diode is connected to the source of the MOSFET transistor, and the second terminal of the first protection diode is connected to the gate of the MOSFET transistor. Similarly, each power supply circuit further includes a second protection diode connected between the source and the drain of the MOSFET transistor.

[0054] The first protection diode is added to protect the MOSFET transistor from an overvoltage on its gate (which may damage it or even make it inoperable) by breaking the insulation between the gate and the channel, which can only withstand + / −20V continuously and + / −30V transiently.

[0055] The role of the second protection diode is to protect the MOSFET transistor from the reverse drain-source voltage that may occur when the voltage of the first power bus appears only after the voltage of the second power bus. Different power buses have their own transformer windings and smoothing capacitors respectively, and thus have different time constants.

[0056] According to the fifth embodiment, each power supply circuit further includes a capacitor mounted in parallel with the fourth diode. This capacitor makes it possible to eliminate the interference peaks generated by the diode when the MOSFET transistor switches, and the first terminal of the diode is connected to the source of the MOSFET transistor. The harmonic distortion (THD) is also improved. This harmonic distortion is a measure of the linearity of the process being implemented. It is calculated by comparing the output signal of the device to a perfect sine wave input signal.

[0057] In practice, the preamplification stage is connected to the first power bus of each power supply circuit via a circuit for damping the power fluctuations of the first power bus, and the power fluctuation damping circuit includes at least one capacitor and at least one resistor mounted as a low-pass filter. In other words, the resistor is connected in series with the capacitor, and the capacitor is connected to ground.

[0058] This assembly makes it possible to isolate noise and voltage dips. This phenomenon occurs especially when the high-voltage amplifier delivers a high current. The capacitor then acts as an energy storage unit.

[0059] Advantageously, the power fluctuation damping circuit further includes an additional capacitor mounted in parallel with at least one capacitor. The capacitors mounted in parallel have a more conservative value (typically 10 3 times lower). It makes it possible to suppress high-frequency interference.

[0060] According to certain embodiments of the present invention, the feedback applied to the preamplifier stage supplies a signal proportional to the current passing through the loudspeaker. This embodiment makes it possible to obtain a high-output current amplifier. As described with reference to Figure 2 of the prior art, high-output current amplifiers of this category have the same topology as those for high-output voltage amplifiers (i.e., a preamplifier stage connected to the amplification stage). However, the feedback applied to the preamplifier stage is different.

[0061] By using the power supply circuit of the present invention for the high-output current amplifier, the high-output current amplifier has a very limited consumption.

[0062] In fact, when the amplifier delivers a low voltage, the power supply circuit of the present invention will not become active. Therefore, the power supplied by the power supply will be equal to the product of the voltage delivered by a lower-power power bus instead of the maximum voltage delivered by a single power bus for a standard class AB amplifier, multiplied by the output current. At equal power, and assuming, for example, that the voltage delivered by a lower-power power bus is equal to half that of a higher-power power bus, half of the power will be supplied by the power supply. The transistor, which dissipates the difference between the power supplied by the power supply and the power supplied to the loudspeaker, will heat up significantly less.

[0063] The manner in which the present invention is embodied, and the resulting advantages therefrom, will be clearly apparent from the following description of the embodiments, supported by the accompanying drawings.

Brief Description of the Drawings

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Figure 18a

Figure 18b

Figure 19

Embodiments for Carrying Out the Invention

[0065] As shown in FIGS. 5a to 5b, the high-power amplifier 102 of the present invention is symmetric, and it includes an upper part and a lower part. The upper part amplifies the positive half-wave of the input signal S1, and the lower part amplifies the negative half-wave of the input signal S1.

[0066] The high-power amplifier 102 includes a preamplification stage. The preamplification stage receives an input signal S1 and supplies signals coming from the collectors of transistors Q5 and Q6 via a network composed of resistors R23 and R57 (mounted in parallel with capacitors C7 and C8). These signals are supplied to the power amplification stage 302 based on transistors Q8 and Q9. The latter supplies an output signal 3 intended to power the loudspeaker R44. Feedback supplies an image of the output signal 3 to the preamplification stage 201.

[0067] Also, the high-power amplifier 102 includes an upper power supply circuit 155a and a lower power supply circuit 155b. The upper power supply circuit 155a is connected to the upper part of the power amplification stage 302, and the lower power supply circuit 155b is connected to the lower part of the power amplification stage 302.

[0068] The preamplification stage 301 includes two differential pairs 110a and 110b, which respectively include two transistors Q1, Q2 and Q3, Q4 that are mirror-mounted to each other. Accordingly, the emitters of transistors Q1 and Q2 are connected to the -65V power bus via resistors R2, R3 and a first constant current source I1, while the emitters of transistors Q3 and Q4 are connected to the +65V power bus via resistors R4, R5 and a second current source I2 of the same value.

[0069] Current sources I1 and I2 each include transistors Q23 and Q24. The collectors of transistors Q23 and Q24 are connected to resistors R2, R3 and R4, R5 respectively. The emitters of transistors Q23 and Q24 are connected to resistors R6 and R10. The second terminal of resistor R6 is connected to the -65V power bus on one hand and to ground via capacitor C11 mounted in series with resistor R46 on the other hand. The second terminal of resistor R10 is connected to the +65V power bus on one hand and to ground via capacitor C12 mounted in series with resistor R48 on the other hand.

[0070] Diodes D1 and D2 are mounted between the bases of transistors Q23 and Q24 and the second terminals of resistors R6 and R10. On the one hand, resistors R45 and R47 are mounted between the bases of transistors Q23 and Q24 and the interconnection points between capacitors C11, C12 and resistors R46, R48.

[0071] The collectors of transistors Q2 and Q4 can be directly connected to the +65V and -65V power buses respectively. Alternatively, the collectors of transistors Q2 and Q4 can be connected to the +65V and -65V power buses respectively via power fluctuation damping circuits 304 and 305.

[0072] Power fluctuation damping circuits 304 and 305 include resistors R52 and R55. Resistors R52 and R55 are mounted in series with capacitors C15 and C19 connected to ground. The second terminals of resistors R52 and R55 are connected to the + / -65V power buses. Advantageously, another capacitors C16 and C20 can be mounted in parallel with capacitors C15 and C19. In practice, capacitors C15 and C19 have values between 150 μF and 300 μF, while capacitors C16 and C20 have values between 150 nF and 300 nF.

[0073] The collectors of transistors Q1 and Q3 are connected to the +65V and -65V power buses via resistors R1 and R11, and preferably via power fluctuation damping circuits 304 and 305, respectively. In the absence of feedback, the gain of the first preamplification stage 102 depends on the resistor ratios R1 / R2 and R11 / R4.

[0074] The bases of transistors Q1 and Q3 are connected to each other and to ground via resistor R7. Also, the bases of transistors Q2 and Q4 are connected to each other. The bases of transistors Q1 and Q3 are supplied with the input signal S1. A voltage source V1 (connected between point S1 and ground) represents the generator of the input signal S1. An intermediate filter circuit can be inserted between the input signal S1 and the bases of transistors Q1 and Q3. This circuit includes, for example, a band-pass filter which includes resistor R9 and capacitor C10 (which is connected to ground), as well as two capacitors C1 and C6 mounted in parallel.

[0075] The bases of transistors Q2 and Q4 are connected to the loudspeaker R44 via resistor R18 and are configured to form the feedback applied to the preamplification stage 301. The collectors of transistors Q1 and Q3 ensure the connection between the preamplification stage 301 and circuits 306, 303, 307 and resistors R12, R13.

[0076] The power amplification stage 302 includes two transistors Q8 and Q9, and the two transistors Q8 and Q9 are connected to the preamplification stage 301 via circuits 306 and 307 by their respective bases.

[0077] Circuits 306 and 307 include transistors Q5 and Q6. The emitters of transistors Q5 and Q6 are connected to the + / -65V voltage bus via resistors R12 and R13, and the bases of transistors Q5 and Q6 are connected to the collectors of transistors Q1 and Q3. Capacitors C2 and C3 are connected between the bases and collectors of transistors Q5 and Q6 to improve the stability of the amplifier. The collectors of transistors Q5 and Q6 are connected on the one hand to resistors R57 and R23 mounted in parallel with capacitors C8 and C7, and on the other hand to bias circuit 303. Bias circuit 303 includes transistor Q7. The emitter of transistor Q7 is connected to the collector of transistor Q5, and the collector of transistor Q7 is connected to the collector of transistor Q6. Resistor R14 is mounted between the collector and base of transistor Q7, and another resistor R15 is mounted between the emitter and base of transistor Q7. Finally, capacitor C5 (for example, having a value of 1 μF) is connected between the emitter and collector of transistor Q7. This capacitor C5 improves the stability of the amplifier. Alternatively, resistors R13 and R12 can be connected to the +65V and -65V power buses via power fluctuation damping circuits 304 and 305, respectively.

[0078] Circuits 306 and 307 perform a second voltage amplification. The gain of this amplification is proportional to the ratio of the "collector-seen" resistance to the resistance present on the emitters of Q5 and Q6. When one of transistors Q5 and Q6 conducts, its dual is cut off. Thus, the conducting transistor exhibits a very high resistance and therefore a very large voltage gain.

[0079] The power amplification stage 302 further includes two transistors Q10 and Q11, and the bases of the two transistors Q10 and Q11 are respectively connected to the emitters of transistors Q8 and Q9. This so-called "Darlington" configuration makes it possible to increase the current gain. The emitters of transistors Q8 and Q10 are connected to the loudspeaker R44 by their respective resistors R16 and R19, while the emitters of transistors Q9 and Q11 are connected to the loudspeaker R44 by their respective resistors R17 and R20. For example, they have their respective quiescent currents, and the quiescent currents are equal to 6 mA for transistors Q8 and Q9 and equal to 75 mA for transistors Q10 and Q11.

[0080] The power amplification stage 302 is connected to two power supply circuits 155a and 155b at the collector portions of transistors Q8 to Q11. These power supply circuits 155a and 155b are connected to two voltage buses having individual levels V+ and V++. Therefore, the power supply circuits 155a and 155b make it possible to select one or the other of these voltage levels according to the amplification requirements. Typically, the first power bus delivers + / -65 V, and the second power bus delivers + / -35 V. The second power bus is intended to be used to power the power amplification stage 302 when the output signal to be generated does not have a very high voltage (typically less than 27 V).

[0081] Due to the relatively low current passing through transistors Q8 and Q9 (typically less than 10% of the current passing through transistors Q10 and Q11), the collectors of Q8 and Q9 can be directly connected to the first power bus V++, and this does not cause significant additional power dissipation. This embodiment improves the stability of the amplifier from the viewpoints of its phase margin and its gain margin.

[0082] In addition, the bases of transistors Q2 and Q4 are connected to a protection line, which includes a resistor R28 mounted in series with a capacitor C4 connected to ground. This assembly is a voltage divider. In fact, capacitor C4 behaves like a short circuit when the voltage flowing through the circuit is alternating current. On the other hand, when the voltage flowing through the circuit is direct current, capacitor C4 behaves like an open circuit. In this case, the output of the high-power amplifier 100 is directly connected to point S2. The voltage gain of the high-power amplifier 100 then becomes equal to 1, which makes it possible to limit any undesirable DC component that may occur above the voltage applied to the terminals of the loudspeaker R44.

[0083] Several embodiments are possible for the power supply circuits 151 - 155, 155a, 155b.

[0084] For all the following embodiments, the signal numbered 1 represents the gate signals of the MOSFET transistors M1, M2. The output signal numbered 3 represents the output signal of the amplifier, i.e., the signal at the terminals of the loudspeaker R44. The output signal numbered 2 represents the output signals of the power supply circuits 151 - 155, 155a, 155b, i.e., the signals present on the collectors of the transistors Q8 and Q10.

[0085] In the remainder of the description, only the upper power supply circuit is illustrated, but FIGS. 5a - 5b make it possible to understand the positioning of the corresponding components for the lower power supply circuit.

[0086] As shown in FIG. 6, in the first embodiment, the power supply circuit 151 includes MOSFET transistors M1 and M2. The MOSFET transistors M1 and M2 are directly connected to the first power bus V++ by their drains, and are connected to the second power bus V+ via the fourth diodes D3 and D11 by their sources. The fourth diodes D3 and D11 can be conventional diodes or Schottky diodes. In practice, the anode of the fourth diode D3 is connected to the second power bus V+, and its cathode is connected to the output signal numbered 2 representing the output signals of the power supply circuits 151 to 155, 155a, and 155b. The cathode of the fourth diode D11 is connected to the second power bus V+. The MOSFET transistors M1 and M2 are blocked with respect to voltages below the threshold (typically 35V), and then switch and operate linearly when this threshold is exceeded. The MOSFET transistors M1 and M2 allow the first power bus V++ to pass when a control voltage greater than the threshold is applied thereto. This voltage is controlled by the association of the sub-circuit 131 for assisting charging, the sub-circuit 141 for assisting discharging, and the voltage shift sub-circuit 161.

[0087] The sub-circuit 131 for assisting charging includes first resistors R24 and R31. The first resistors R24 and R31 are connected between the gates of the MOSFET transistors M1 and M2 and the interconnection points A1 and A2.

[0088] The sub-circuit 141 for assisting discharging includes transistors Q12 and Q13. The emitters of transistors Q12 and Q13 are connected to the gates of MOSFET transistors M1 and M2 on one hand, and to the sub-circuit 131 for assisting charging on the other hand. The collectors of transistors Q12 and Q13 are connected to the output signal 2 of the power supply circuit 151 via the second resistors R8 and R27. The bases of transistors Q12 and Q13 are connected to the interconnection points A1 and A2 via the third resistors R21 and R39.

[0089] The voltage shift sub-circuit 161 includes the first capacitors C18 and C23 mounted in parallel with the first diodes D8 and D10. The cathode of the first diode D8 is connected to the first interconnection node N1, and the anode of the first diode D8 is connected to the second interconnection node N2. The diode D10 is connected reversely as shown in FIGS. 5a to 5b, that is, its cathode is connected to the interconnection node N3 and its anode is connected to the interconnection node N4. The first interconnection node is connected to the interconnection point A1, and the second interconnection node is connected to the loudspeaker R44.

[0090] The voltage shift sub-circuit ensures that the gate potential of the MOSFET transistor M1 is always 15V higher than that of the amplifier output.

[0091] In addition, the Darlington circuit composed of transistors Q8 and Q10 requires a dropout voltage of 5V (i.e., a voltage equal to the difference between the input voltage above the collector of transistor Q8 and the output voltage at the emitter of transistor Q10). On the other hand, MOSFET M1 requires a dropout voltage of 10V (i.e., in the case where the current is at its maximum and saturated, a voltage equal to the difference between the input voltage above its gate and the output voltage above its source). Therefore, the voltage shift sub-circuit must compensate for the voltage drops of the two bipolar transistors Q8 and Q10, as well as the voltage drop of MOSFET M1 (i.e., 5 + 10 = 15V).

[0092] The power supply circuit 151 advantageously includes first protection diodes D5, D13. The anode of diode D5 is connected to the output signal 2 of the power supply circuit 151, and its cathode is connected to the gate of MOSFET transistor M1. The cathode of diode D13 is connected to the output of the power supply circuit 155b, and its anode is connected to the gate of MOSFET transistor M2. Similarly, the power supply circuit 151 includes second protection diodes D4, D12. The cathode of diode D4 is connected to the source of MOSFET transistor M1, and its anode is connected to the source of MOSFET transistor M1. The cathode of diode D12 is connected to the source of MOSFET transistor M2, and its anode is connected to the drain of MOSFET transistor M2.

[0093] With such an assembly, the different signals obtained are illustrated in FIGS. 7 and 8.

[0094] The signal illustrated in FIG. 7 corresponds to the signal obtained by a sine curve of 20 kHz supplied at the input of the high-power amplifier 102.

[0095] Therefore, we notice that the output signal 3 is distorted at the peak of the sine curve presenting a triangular appearance. Therefore, it is not possible to correctly reproduce the 20 kHz sine curve. On the other hand, we do not observe abnormal voltage peaks. Therefore, the power loss is limited.

[0096] The signal illustrated in FIG. 8 corresponds to the signal acquired by the 1 kHz sine curve supplied at the input of the high-power amplifier 102.

[0097] Therefore, we notice that the output signal 3 is less distorted than when it is at 20 kHz. To the naked eye, the sine curve of the output signal 3 even seems to be perfectly reproduced. However, it has been found that the harmonic distortion (THD) is greater than 0.1%.

[0098] As illustrated in FIG. 9, in the second embodiment, the voltage shift sub-circuit 162 of the power supply stage 152 further includes second diodes D6, D29 mounted in parallel with the fourth resistors R22, R26. The cathode of the second diode D6 is connected to the interconnection point N1, and the anode of the second diode D6 is connected to the third interconnection node N10. The diode D29 is connected in reverse as illustrated in FIGS. 5a - 5b, that is, its cathode is connected to the interconnection node N20 and its anode is connected to the interconnection node N4.

[0099] With such an assembly, the different signals obtained are illustrated in FIGS. 10 and 11. The signal illustrated in FIG. 10 corresponds to the signal acquired by the 20 kHz sine curve supplied at the input of the high-power amplifier 102.

[0100] Therefore, we notice that the output signal 3 is distorted at the peak of the sine curve presenting a triangular appearance. Therefore, it is not possible to correctly reproduce the 20 kHz sine curve.

[0101] The signal illustrated in FIG. 11 corresponds to the signal acquired by the sine curve of 1 kHz frequency supplied at the input of the high-power amplifier 102.

[0102] To the naked eye, the sine curve of the output signal 3 is completely reproduced on the positive half-wave and appears slightly distorted on the negative half-wave. The harmonic distortion THD is equal to 0.45%. The reason is that the observed distortion corresponds to the generation of harmonics.

[0103] Therefore, the addition of these components does not help reduce the distortion observed on the amplifier output signal. The addition of the second diodes D6, D29 and the fourth resistors R22, R26 degrades the dynamic performance of the circuit. To be beneficial, i.e., to improve the degradation at low and high frequencies, more complex circuits are required. To obtain a performance gain, it is possible to add other elements around the transistors Q12, Q13.

[0104] As illustrated in FIG. 12, in the third embodiment, the sub-circuit 132 for assisting in charging the power supply stage 153 further includes a circuit branch, and the circuit branch includes the third diodes D9, D14 in series with the fifth resistors R29, R30. The fifth resistors R29, R30 are mounted in parallel with the first resistors R24, R31. The cathode of the third diode D9 is connected, for example, to the gate of the MOSFET transistor M1. The anode of the third diode D14 is connected to the gate of the MOSFET transistor M2. Alternatively, the components D9, R29 and D14, R30 can be reversed so that the third diodes D9, D14 are connected to the gates of the MOSFET transistors M1, M2 via the resistors R29, R30.

[0105] Such an assembly obtains different signals, as illustrated in FIG. 13. The latter corresponds to the signal obtained by the sine curve of 20 kHz provided at the input of the high-power amplifier 102.

[0106] We observe that the output sine curve corresponding to the output signal numbered 3 is well restored. On the other hand, the output signal 2 (representing the output voltage of the power supply circuit 153) has distortion between 0 μs and 5 μs and between 18 μs and 20 μs. The THD is equal to 0.26%. The addition of these components here makes it possible to improve the distortion for the sine curve input signal up to a frequency of 20 kHz.

[0107] As illustrated in FIG. 14, in the fourth embodiment, the voltage shift sub-circuit of the power supply stage 154 further includes third capacitors C21, C24 and second capacitors C17, C22. The third capacitors C21, C24 are mounted in parallel with fourth resistors R22, R26 and second diodes D6, D29. The second capacitors C17, C22 are mounted in parallel with first diodes D8, D10 and first capacitors C18, C23.

[0108] Different signals obtained by such an assembly are illustrated in FIG. 15. The latter corresponds to the signal obtained by the sine curve of 20 kHz supplied at the input of the high-power amplifier 102.

[0109] Therefore, we observe that signal 2 has less interference, but the switching of the fourth diode D3 still causes interference, especially between 45 μs and 50 μs.

[0110] In fact, the second capacitors C17, C22 (using, for example, an electrochemical technology) have a fairly large value (typically between 5 μF and 15 μF) and constitute an energy storage section, while the first capacitors C18, C23 (using, for example, an electrochemical plastic film technology) have a lower value (typically between 50 nF and 150 nF) and make it possible to smooth high-frequency interference. The THD is reduced to 0.21%.

[0111] This association makes it possible to make the circuit more efficient in the transient phases of signal growth and decay.

[0112] As shown in FIGS. 5a - 5b and FIG. 16, in the fifth embodiment, the power supply stages 155, 155a, 155b further include fourth capacitors C14, C25 mounted in parallel with the fourth diodes D3, D11.

[0113] The different signals obtained by such an assembly are shown in FIG. 17. The latter corresponds to the signal obtained by the sine curve of frequency 20 kHz supplied at the input of the high - power amplifier 102.

[0114] We observe that the interference generated by the fourth diodes D3, D11 disappears between 45 μs and 50 μs. This results in a slight drop in THD from 0.21% to 0.2%.

[0115] Above, the present invention has been described with reference to FIGS. 5a - 5b to FIG. 17 with respect to the high - power audio amplifier 102 that makes it possible to supply voltage to the loudspeaker R44. However, it is also possible to use the power supply circuit of the present invention for a high - power current audio amplifier, that is, for supplying current to a loudspeaker.

[0116] To do this, as shown in FIGS. 18a to 18b, a current measuring resistor R61 is inserted between the loudspeaker R44 and ground. Further, the current amplifier 103 does not have a protection line 403. The bases of the transistors Q2 and Q4 are connected to an interconnection point positioned between the resistor R61 and the loudspeaker R44 via a capacitor C40. Therefore, this capacitor C40 allows only the AC component of the signal to pass through.

[0117] Therefore, in this configuration, the loudspeaker R44 is traversed by an alternating current, and its image is applied to point S2. As a result, the transconductance of the amplifier is equal to 1 / R61 with respect to the AC signal.

[0118] Alternatively, to protect the loudspeaker R44 and the amplifier itself, a resistor can be added to the feedback between point S2 and the output of amplifier 3. In the case where there is a DC component at the terminals of the loudspeaker R44, the DC component is applied at the bases of the transistors Q2 and Q4 via the resistor R18. The feedback tends to cancel this DC component. In addition, the resistor R18 helps to limit the gain of the amplifier in the absence of the loudspeaker R44 and also prevents it from oscillating.

[0119] When the current is alternating current, capacitor C40 has an impedance that can be ignored compared to the value of resistor R18. During normal operation, that is, when there is no DC component and loudspeaker R44 is actually present at the amplifier output, resistor R18 has little effect. On the other hand, when loudspeaker R44 is not present at the amplifier output, we can consider that point S2 is connected to the amplifier output via resistor R18 on one hand and to ground via resistor R61 on the other hand. The reason is that capacitor C40 behaves like a short circuit for alternating current. Therefore, the voltage amplification is limited to (R18 + R61) / R61. The reason is that the output voltage of the amplifier multiplied by R61 / (R18 + R61) is compared with the input voltage applied at point S1 by the differential pair formed by transistors Q1 / Q2 and Q3 / Q4. Then, the amplifier will not supply its maximum output voltage, which can be dangerous. Similarly, when a DC component is present and loudspeaker R44 is present or not present at the amplifier output, the capacitor behaves like an open circuit, and therefore the DC component is reinjected at point S2 via resistor R18. Therefore, the voltage gain is limited to 1 with respect to the DC voltage, which poses no risk of damaging loudspeaker R44.

[0120] In another variant, it is possible to add a current amplifier protection circuit. To do this, as shown in FIG. 19, the interconnection point P1 located between the resistor R61 and the loudspeaker R44 is connected to the first terminal of the resistor R70. In this embodiment, the second terminal of the resistor R70 is connected to the collector of the transistor Q16. Also, the collector of the transistor Q16 is connected to the base of the second transistor Q15. The voltage divider is composed of the resistors R71 and R72 and makes it possible to adapt the current threshold (from which the protection circuit starts to act). The first terminal of the resistor R71 is connected to the second power bus V+ having a value of 32V. The second terminal of the resistor R71 is connected to the base of the transistor Q15 and the collector of the transistor Q16. The first terminal of the resistor R72 is connected to the second terminal of the resistor R70, and the second terminal of the resistor R72 is connected to ground. Thus, the conduction threshold voltage of the transistor Q15 is shifted by V+*R72 / (R71+R72). This makes it possible to increase the sensitivity, i.e., to lower the current threshold at which the protection acts.

[0121] Preferably, transistor Q15 is a Darlington transistor. This makes it possible to limit the distortion caused by the circuit by drawing a lower current at the terminals of the measuring resistor R61 while maintaining sufficient sensitivity due to the divider network R71 / R72. Another divider bridge composed of resistors R73 and R74 is inserted between point 3 and ground. The first terminal of resistor R73 is connected to point 3. The second terminal of resistor R73 is connected to the base of transistor Q16 and to the first terminal of resistor R74. The second terminal of resistor R74 is connected to ground. Thus, the voltage threshold (from which current protection starts and is neutralized) is adapted. The emitters of transistors Q16 and Q15 are connected together and also connected to ground. The collector of transistor Q15 is connected to the base of transistor Q8 via diode D21. The cathode of diode D21 is connected to the collector of transistor Q15.

[0122] This circuit has to be mirror - replicated to manage current protection during the negative half - wave. Then, the NPN transistors are replaced by PNP transistors.

[0123] This circuit makes it possible to limit the risk of power failure of the current amplifier, especially when it is overloaded or when its output is short - circuited. In fact, in these cases, the product of the output current and the voltage of the power bus will be completely dissipated by the transistors, and they may be damaged.

[0124] When the current in the current measuring resistor R61 is sufficient to turn on the transistor Q15 by the circuit of FIG. 19, the transistor Q15 can retreat the signal coming from the base of the transistor Q8 toward the ground via the diode D21 and is configured to cut it off. On the other hand, when the voltage at the terminal of the loudspeaker R44 is sufficient to turn on the transistor Q16, the signal coming from the base of the transistor Q15 will be bypassed to the ground and it is the latter transistor that will be cut off. Therefore, the protection circuit is neutralized when there is sufficient voltage at the amplifier output.

[0125] In conclusion, the present invention makes it possible to obtain a high-output audio amplifier that can limit the distortion identified on the signal, thus improving the efficiency of the amplifier and reducing saturation.

Description of the symbols

[0126] 1 Gate signal of the MOSFET transistor M1 2 Output signal of the power supply circuit 150 3 Output signal of the amplifier, signal at the terminal of the loudspeaker R44 100 High-output amplifier 101 Current amplifier 102 High-output amplifier 103 Current amplifier 110a, 110b Differential pair 131 Sub-circuit for assisting charging 132 Sub-circuit for assisting charging 140a Upper part 140b Lower part 141 Sub-circuit for assisting discharging 150 Power supply circuit 151 Power supply circuit 152 Power supply stage 153 Power supply stage 154 Power supply stage 155 Power Supply Stage 155a Power Supply Circuit 155b Power Supply Circuit 161 Voltage Shift Sub - Circuit 162 Voltage Shift Sub - Circuit 163 Voltage Shift Sub - Circuit 201 Pre - Amplification Stage 202 Power Amplification Stage 203 Amplification Stage 204 Power Amplification Stage 301 Pre - Amplification Stage 302 Power Amplification Stage 303 Bias Circuit 304 Power Fluctuation Damping Circuit 305 Power Fluctuation Damping Circuit 306 Circuit 307 Circuit 403 Protection Line A1 Interconnection Point A2 Interconnection Point C1 Capacitor C2 Capacitor C3 Capacitor C4 Capacitor C6 Capacitor C7 Capacitor C8 Capacitor C10 Capacitor C11 Capacitor C12 Capacitor C14 Fourth Capacitor C15 Capacitor C16 Capacitor C17 Second Capacitor C18 First Capacitor C19 Capacitor C20 Capacitor C21 Third Capacitor C22 Second Capacitor C23 First Capacitor C24 Third Capacitor C25 Fourth Capacitor D1 Diode D2 Diode D3 Fourth Diode D4 Second Protection Diode D5 First Protection Diode D6 Second Diode D8 First Diode D9 Third Diode D10 First Diode D11 Fourth Diode D12 Second Protection Diode D13 First Protection Diode D14 Third Diode D15 Diode D29 Second Diode I First Constant Current Source, Second Current Source I1 First Constant Current Source I2 Second Current Source M1 MOSFET Transistor M2 MOSFET Transistor N1 First Interconnection Node N2 Second Interconnection Node N3 Interconnection Node N4 Interconnection Node N10 Third Interconnection Node N20 Interconnection Node P1 Interconnection Point Q1 Transistor Q2 Transistor Q3 Transistor Q4 Transistor Q5 Transistor Q6 Transistor Q7 Transistor Q8 Transistor Q9 Transistor Q10 Transistor Q11 Transistor Q12 Transistor Q13 Transistor Q15 Transistor Q16 Transistor Q23 Transistor Q24 Transistor R1 Resistor R2 Resistor R3 Resistor R4 Resistor R5 Resistor R6 Resistor R7 Resistor R8 Second Resistor R9 Resistor R10 Resistor R11 Resistor R12 Resistor R13 Resistor R14 Resistor R15 Resistor R16 Resistor R17 Resistor R18 Resistor R19 Resistor R20 Resistor R21 Resistor R22 Fourth Resistor R23 Resistor R24 First Resistor R26 Fourth Resistor R27 Second Resistor R28 Resistor R29 Fifth Resistor R30 Fifth Resistor R31 First Resistor R39 Resistor R44 Loudspeaker R45 Resistor R46 Resistor R47 Resistor R48 Resistor R52 Resistor R55 Resistor R57 Resistor R61 Resistor S1 Point, Input Signal S2 Point T1 Voltage Source V1 Voltage Source

Claims

1. A high-power audio amplifier (102) intended to control at least one loudspeaker (R44), the amplifier comprising: - A preamplification stage (201, 301) for receiving an input signal (S1); - A power amplification stage (202-203, 302) connected to the preamplification stage (201, 301) and supplying an output signal (3) intended to power the at least one loudspeaker (R44), the preamplification stage (201, 301) and the power amplification stage (202-203, 302) including upper and lower parts mounted mirroring each other, the power amplification stage (202-203, 302); - Feedback for supplying an image of the output signal (3) to the preamplification stage (201, 301); - An upper power supply circuit (151-155, 155a) connected to the upper part of the power amplification stage (202-203, 302) and enabling it to be powered by a first or second power bus (V++, V+), the upper power supply circuit (151-155, 155a); - A lower power supply circuit (155b) connected to the lower part of the power amplification stage (202-203, 302) and enabling it to be powered by a first or second power bus, the lower power supply circuit (155b); and comprising - Each power supply circuit (151 to 155, 155a, 155b) includes MOSFET transistors (M1, M2) and monitoring means, and the MOSFET transistors (M1, M2) are controlled by the monitoring means and are adapted to perform switching between one or the other of the two power buses (V++, V+). The MOSFET transistors (M1, M2) are connected to the second power bus (V+) via fourth diodes (D3, D11). The first terminal of the fourth diode (D3, D11) is connected to the source of the MOSFET transistor (M1, M2), and the drain of the MOSFET transistor (M1, M2) is connected to the first power bus (V++). In the high-power audio amplifier (102), Each power supply circuit (151 to 155, 155a, 155b) is, - Sub-circuits (131 to 133) for assisting in charging the MOSFET transistors (M1, M2), the sub-circuits (131 to 133) for assisting in charging including at least first resistors (R24, R31), the first terminal of the first resistor (R24, R31) being connected to the gate of the MOSFET transistor (M1, M2), and the second terminal of the first resistor (R24, R31) being connected to an interconnection point (A1). Sub-circuits (131 to 133) for assisting in charging, - A sub - circuit (141) for assisting in discharging the MOSFET transistors (M1, M2), wherein the sub - circuit (141) for assisting in discharging includes at least second and third resistors (R8, R27, R21, R39) and bipolar transistors (Q12, Q13). The base of the bipolar transistors (Q12, Q13) is connected to the first terminal of the third resistor (R21, R39), its emitter is connected to the gate of the MOSFET transistors (M1, M2), its collector is connected to the source of the MOSFET transistors (M1, M2) via the second resistor (R8), and the second terminal of the third resistor (R21, R39) is connected to the interconnection point (A1, A2). A sub - circuit (141) for assisting in discharging. - Voltage - shift sub - circuits (161 - 163), wherein the voltage - shift sub - circuits (161 - 163) include first diodes (D8, D10) mounted in parallel with first capacitors (C18, C23). The first terminal of the first diodes (D8, D10) and the first terminal of the first capacitors (C18, C23) are connected to a first interconnection node (N1, N4), and the first interconnection node (N1, N4) itself is connected to the interconnection point (A1, A2) of the sub - circuit (141) for assisting in discharging. The second terminal of the first diodes (D8, D10) and the second terminal of the first capacitors (C18, C23) are connected to a second interconnection node (N2, N3), and the second interconnection node (N2, N3) itself is connected to the output signal (3). Voltage - shift sub - circuits (161 - 163). A high - output audio amplifier (102), characterized by further comprising the above.

2. The voltage shift sub-circuits (161-163) further include at least fourth resistors (R22, R26) and second diodes (D6, D29), the fourth resistors (R22, R26) and the second diodes (D6, D29) are mounted in parallel, a first terminal of the second diodes (D6, D29) and a terminal of the fourth resistors (R22, R26) are connected to the interconnection points (A1, A2), and a second terminal of the fourth resistors (R22, R26) and a second terminal of the second diodes (D6, D29) are connected to a third interconnection node (N10). The amplifier according to claim 1, characterized in that.

3. The sub-circuits (131-133) for assisting the charging further include fifth resistors (R29, R30), the fifth resistors (R29, R30) are mounted in series with third diodes (D9, D14), and the fifth resistors (R29, R30) and the third diodes (D9, D14) are mounted in parallel with a branch of the sub-circuits (131-133) for assisting the charging including the first resistors (R24, R31). The amplifier according to claim 1 or 2, characterized in that.

4. The voltage shift sub-circuits (161-163) further include second capacitors (C17, C22) and third capacitors (C21, C24), the second capacitors (C17, C22) are mounted in parallel with the first capacitors (C18, C23) and the first diodes (D8, D10), and the third capacitors (C21, C24) are mounted in parallel with the second diodes (D6, D29) and the fifth resistors (R22, R26). The amplifier according to claim 1, characterized in that.

5. Each power supply circuit (151-155, 155a, 155b) includes a first protection diode (D5, D13), a first terminal of the first protection diode (D5, D13) is connected to the source of the MOSFET transistors (M1, M2), and a second terminal of the first protection diode (D5, D13) is connected to the gate of the MOSFET transistors (M1, M2). The amplifier according to claim 1, characterized in that.

6. The amplifier according to claim 1, wherein each power supply circuit (151 to 155, 155a, 155b) further includes a second protection diode (D4, D12) connected between the source and the drain of the MOSFET transistor (M1, M2).

7. The amplifier according to claim 1, wherein each power supply circuit (151 to 155, 155a, 155b) further includes a fourth capacitor (C14, C25) mounted in parallel with the fourth diode (D3, D11).

8. The preamplification stage (201, 301) is connected to the first power bus (V++) of each power circuit (151 to 155, 155a, 155b) by the power fluctuation damping circuit (304, 305) of the first power bus (V++), and the power fluctuation damping circuit (304, 305) includes at least one capacitor (C15, C19) and at least one resistor (R52, R55) mounted as a low-pass filter. The amplifier according to claim 1, characterized in that.

9. The amplifier according to claim 8, wherein the power fluctuation damping circuit (304, 305) further includes an additional capacitor mounted in parallel with the at least one capacitor (C16, C20).

10. The feedback applied to the preamplification stage supplies a signal proportional to the current passing through the loudspeaker. The amplifier according to claim 1, characterized in that.

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