TWM524017U - Power amplifying apparatus - Google Patents

Description

Power amplifier

This creation is about a power amplifier, especially an audio power amplifier with a booster and dynamic power range control.

According to the technical field of Audio Power Amplifier, various circuit topologies have been developed so far, including: Class A, Class B, Class AB, Class D, Class G, etc. For example, as shown in the first figure, a class D audio amplifier has a comparison circuit 11, and the two input terminals of the comparison circuit 11 respectively receive an analog audio signal 111 and a triangular wave signal 112, and can be compared in the comparison circuit. The output of 11 receives a pulse width modulation signal, which is transmitted to a driving and output stage 12 for driving and controlling the power crystal in the driving and output stage 12 to obtain an amplified pulse. The widened signal is converted, and finally, the amplified pulse width modulation signal is filtered through a low pass filter 13 to filter out the high frequency carrier, and the amplified audio signal is restored and outputted by a speaker 2.

The conventional audio power amplifier can realize the function of amplifying the audio signal, but still faces the following technical problems and challenges: First, for the currently popular mini-audio products such as the portable Bluetooth speaker, due to its speaker The limitation of the size of the monomer, the user often only makes a trade-off between the convenience of carrying and the shocking effect of the hearing, therefore, it is necessary to develop an audio amplifier that is miniaturized and can simultaneously have the subwoofer enhancement function; Second, with A problem with the aforementioned bass-enhanced audio amplifier is that when the level of the bass audio is dynamically increased so as to exceed the supply voltage of the power output stage, the amplified audio output signal is clipped. The phenomenon of saturation distortion is formed, causing the speaker to break or pop, which seriously affects the listening experience. Therefore, how to make the audio power amplifier dynamically adjust the power supply voltage to maintain sufficient headroom when the bass level is strengthened. In order to maintain a sufficient output dynamic range, it becomes a technical subject with urgency and practicality.

In view of the conventional audio power amplifier, it is difficult to simultaneously achieve the design goal of miniaturization and enhanced bass performance. Therefore, the purpose of this creation is to develop a power amplifying device that can keep the overall circuit integrated and simultaneously realize the bass enhancement effect.

Another object of the present invention is to develop a power amplifying device that can simultaneously implement a dynamic power range control function when the bass is enhanced.

In order to achieve the above objective, the present invention provides a power amplifying device comprising: a preamplifier stage, a preamplifier and a bass boost control circuit connected to the preamplifier in a feedback manner; a power amplification The stage is provided with an audio power output stage and a dynamic power supply voltage switching switch. The audio power output stage is electrically connected to the preamplifier stage, and one of the dynamic power voltage switching switches is connected to a small fixed power supply voltage; The power supply circuit is provided with an amplitude and phase detecting circuit, a driving circuit and a power output stage. The power output stage is connected to another input end of the dynamic power voltage switching switch for enhancing the bass signal when the current amplifier stage is enhanced. A dynamic supply voltage greater than the fixed supply voltage is provided to the power amplification stage.

With the above structure, the creation can realize the subwoofer enhancement effect and reduce the circuit. Dimensions, while maintaining the margin and dynamic range of the output, thus achieving a significant increase in product usability and reliability.

[Use]

11‧‧‧Comparative circuit

111‧‧‧ audio signal

112‧‧‧ triangle wave signal

12‧‧‧Drive and output stages

13‧‧‧Low-pass filter

2‧‧‧Speakers

[this creation]

3‧‧‧Preamplifier

31‧‧‧Preamplifier

32‧‧‧ bass boost control circuit

321‧‧‧Active Capacitor Multiplier

4‧‧‧Power amplification stage

41‧‧‧Audio power output stage

42‧‧‧Dynamic power supply voltage switch

421‧‧‧First power supply voltage output

422‧‧‧Second supply voltage input

423‧‧‧Power supply voltage output

5‧‧‧Drive output stage

51‧‧‧Stagnation time control circuit

52‧‧‧Voltage level shifting circuit

6‧‧‧Power supply circuit

61‧‧‧Amplitude and phase detection circuit

62‧‧‧Drive circuit

63‧‧‧Power supply output stage

631‧‧‧ input

632‧‧‧output

64‧‧‧reference voltage control circuit

65‧‧‧Error amplifier bandwidth control circuit

651‧‧‧ first input

652‧‧‧second input

653‧‧‧output

66‧‧‧voltage circuit

7‧‧‧Speakers

R _f1 ‧‧‧first feedback resistor

R _f2 ‧‧‧second feedback resistor

R _IN ‧‧‧Input resistance

The first figure is a schematic block diagram of a conventional Class D amplifier.

The second diagram is a schematic diagram of the architecture of the creation.

The third figure is a schematic diagram of a more specific embodiment of the preamplifier stage of the present creation.

The fourth picture is a schematic diagram of the action of this creation.

It can be noted that the embodiments disclosed below are specifically applicable to various existing power amplifiers such as Class A, Class B, Class AB, Class D, etc., which is not limited in this creation.

Referring to the second figure, the present invention provides a power amplifying device, comprising: a preamplifier stage 3, a preamplifier 31 is disposed in the preamplifier stage 3, and a feedback mode and the front end are provided. The bass boost control circuit 32 connected to the amplifier 31, as shown in the third figure, discloses a pre-amplifier stage 3, in particular a more specific embodiment of the bass boost control circuit 32, in this embodiment. The preamplifier 31 preferably employs a fully differential amplifier having dual outputs, which has better anti-noise interference performance and is suitable for applications requiring high sound quality. Since the full differential amplifier is used here, the number of the bass boost control circuits 32 is two. More specifically, the bass boost control circuit 32 is provided with a first feedback resistor R _f1 and a first feedback The active capacitor multiplying circuit 321 in which the resistor R _{f1 is} connected in parallel, this configuration can produce an effect similar to a low-pass filter, as long as the first feedback resistor Rf1 and the preamplifier 31 are properly configured. The ratio between the input resistors R _1N can make the preamplifier 31 have a larger gain for the low frequency audio signal, thereby achieving the purpose of bass boosting. In addition, the bass boost control circuit 32 can also Further, a second feedback resistor R _f2 is connected in series with the active capacitor multiplying circuit 321 , and the resistance value of the second feedback resistor R _f2 is smaller than the first feedback resistor R _f1 , so that the same bass can be achieved. In addition, in other feasible embodiments, the preamplifier 31 can also use other types of amplifiers, such as a single-ended output differential amplifier, in which only one bass boost control is needed. The circuit 32 can be used; it is worth noting that when the feedback capacitor is selected for the preamplifier 31, in order to make the preamplifier 31 have better low frequency response characteristics, a real subwoofer enhancement effect can be realized (in the human ear) The received audio signal has a frequency range of about 20~20 kHz. Generally, the audio signal in the range of 50~250 Hz can be regarded as a heavy bass. Generally, a sufficiently large capacitor must be used. For example, an nF-class capacitor, but such a large capacitor is difficult to integrate with the preamplifier 31 in a single IC chip, and can only be arranged in the form of discrete components, thereby greatly increasing the size of the board and failing to conform to the portability. For the miniaturization of the audio product, the author uses the active capacitor multiplying circuit 321 as the feedback capacitor of the preamplifier 31, and the active capacitor multiplying circuit 321 is actually an active component (such as an amplifier or An active capacitance multiplier of a transistor, which is configured with a small capacitor in the circuit, and by adjusting and controlling the ratio of different resistors in the circuit, the entire circuit can be equivalent to a larger The specific circuit structure of the active capacitor multiplying circuit 321 is a prior art and is not a technical feature of the present invention, and therefore will not be described in detail herein. Therefore, the present invention only needs to adopt the actual in the active capacitor multiplying circuit 321 . A capacitor with a value of only pF can be equivalent to the effect of the nF capacitor, so that the active capacitor multiplying circuit 321 and the preamplifier 31 can be used in the present creation. Integrated and integrated in the same IC chip, in order to greatly reduce the size of the circuit, so that the creation can simultaneously achieve the bass boost and reduce the size of the circuit; a power amplifier stage 4, the power amplifier stage 4 is provided with an audio power output The audio power output stage 41 is electrically connected to the preamplifier stage 3 for power amplification of the audio signal amplified and outputted through the preamplifier stage 3, so that the power amplifier stage 4 can amplify the power. The audio signal is transmitted to a speaker 7 for audio output. Like a general power output stage, the audio power output stage 41 is usually provided with a power crystal as an energy pass element and in the audio power output stage 41. The remaining detailed structure is well known to those skilled in the art, and will not be further described herein. In addition, a dynamic power supply voltage switch 42 may be disposed in the power amplifier stage 4, and the dynamic power voltage switch 42 has a first The power voltage input terminal 421, a second power voltage input terminal 422, and a power voltage output terminal 423, wherein the first power voltage input terminal 421 is connected a small fixed power supply voltage, such as Vdd, connected to the audio power output stage 41 for transmitting the power supply voltage required by the audio power output stage 41; the foregoing directly after the preamplifier stage 3 The configuration of the connection power amplifier stage 4 can be applied to linear power amplifiers such as Class A, Class B, and Class AB. However, the present invention can further include a driving output stage 5, which is set in the preamplifier. The stage 3 is connected to the power amplifier stage 4, and the drive output stage 5 is respectively connected to the preamplifier stage 3 and the power amplifier stage 4. The drive output stage 5 is provided with a dead time control circuit 51 and a voltage level shift circuit 52 electrically connected to the dead time control circuit 51, the dead time control circuit 51 and the voltage level shift circuit 52 and the preamplifier stage 31 of the preamplifier stage 3, respectively The power amplification stage 4 is electrically connected to the audio power output stage 41. The power supply voltage switch 423 is also connected to the voltage level shifting circuit 52 for transmitting the voltage level shifting. The power supply voltage required by the circuit 52, wherein the dead time control circuit 51 is used to prevent the high side and low side power crystals in the audio power output stage 41 from being simultaneously turned on to cause a short circuit of the power supply. The voltage level shifting circuit 52 is used to raise the voltage level of the audio signal, so that the high-side power crystal can be smoothly driven, thereby making the creation suitable for switching such as a class D amplifier. A power amplifier of the type, further, if a control circuit for switching the enabled state of the drive output stage 5 is configured, the present invention can be applied to a mixture of a linear power amplifier and a switching power. In the power amplifier circuit architecture of the amplifier, the application range and versatility of the present invention can be greatly improved; a power supply circuit 6 is specifically an adaptive boost power converter. When the current amplifier stage 3 is used to enhance the bass audio signal, the power amplifier stage 4 is provided with a dynamic power supply voltage greater than the fixed power supply voltage. The power supply voltage of the amplifier stage 4 can maintain a certain headroom to maintain a sufficient output dynamic range. In this embodiment, the power supply circuit 6 is provided with an amplitude and phase detecting circuit 61, a driving circuit 62, and The power supply output stage 63, wherein the driving circuit 62 includes a reference voltage control circuit 64, an error amplifier bandwidth control circuit 65, and a voltage dividing circuit 66. The error amplifier bandwidth control circuit 65 is usually an error amplifier (Error Amplifier). And the necessary feedback compensation circuit, the feedback compensation circuit is generally composed of capacitors, resistors and the like to regulate the bandwidth of the error amplifier, the transient response and the stability The characteristics are such that the error amplifier achieves a better balance between the response speed to the load change and the stability of the system. The error amplifier bandwidth control circuit 65 has a first input 651, a second input 652, and an output. The end 653, the amplitude and phase detecting circuit 61 and the preamplifier stage 3 respectively have a bass boost control circuit 32, a reference voltage control circuit 64 and an error The second bandwidth 652 of the bulk bandwidth control circuit 65 is electrically connected. The reference voltage control circuit 64 is also electrically connected to the first input end 651 of the error amplifier bandwidth control circuit 65. The error amplifier bandwidth control circuit is further connected. The output end 653 is electrically connected to the input end 631 of the power supply output stage 63. The voltage dividing circuit 66 is connected to the power supply output stage 63 in an feedback manner, and its output end 632 and the error amplifier bandwidth control circuit 65 The second input end 652 and the output end 632 of the power supply output stage 63 are also electrically connected to the second power supply voltage input end 422 of the dynamic power supply voltage switch 42. The amplitude and phase detection circuit 61 is used. Detecting the amplitude and phase of the amplified audio signal through the preamplifier stage 3, and transmitting the detected amplitude signal and phase signal to the reference voltage control circuit 64 and the error amplifier bandwidth control circuit, respectively. 65, the reference voltage control circuit 64 according to the amplitude signal, generating a corresponding reference voltage (reference voltage, V _REF) signal, and then transmits the signals to the reference voltage The first input end 651 of the difference amplifier bandwidth control circuit 65, the internal feedback compensation circuit of the error amplifier bandwidth control circuit 65 can generate and determine the bandwidth and transient response characteristics of the error amplifier according to the phase signal. The output stage 653 of the error amplifier bandwidth control circuit 65 generates a corresponding pulse width control signal according to the signal of the input terminal and transmits it to the power supply output stage 63, and can be generated at the output end 632 of the power supply output stage 63. The dynamic power supply voltage is transmitted to the dynamic power supply voltage switch 42; the working principle and beneficial effects of the present invention are described below: Please refer to the third and fourth figures, when the audio signal is in the middle or high range, The gain generated by the preamplifier stage 3 is small, so that the audio power output stage 41 of the power amplifier stage 4 can eliminate a large power supply voltage, so the dynamic power supply voltage switch 42 switches its switching state, utilizing the first power supply voltage. The fixed power supply voltage connected to the input terminal 421 supplies power to the audio power output stage 41 and the voltage level shift circuit 52; when the audio signal belongs to the bass or In the bass range, the bass boost control circuit 32 can generate a large gain in the preamplifier stage 3, and the amplitude and phase detecting circuit 61 of the power supply circuit 6 detects a large amplitude signal, so that the The reference voltage control circuit 64 can generate a larger reference voltage signal, and can dynamically cause the power supply power output stage 63 to generate a dynamic power supply voltage greater than the fixed power supply voltage. At this time, the dynamic power supply voltage switch 42 can switch the dynamic power supply. In the switch state, the dynamic power supply voltage connected to the second power voltage input terminal 422 is supplied to the audio power output stage 41 and the voltage level shift circuit 52, so that the current amplifier stage 3 enhances the bass audio signal and improves When the level is correct, the power supply circuit 6 can synchronously and dynamically raise the power supply voltage of the audio power output stage 41 to a higher level, so that the power level at this time can be maintained higher than the audio signal level of the bass. Avoiding the saturation distortion caused by the interception of the audio output signal, thus realizing the dynamic power control function, which enables the creation to greatly improve product performance and reliability. Effect.

3‧‧‧Preamplifier

31‧‧‧Preamplifier

32‧‧‧ bass boost control circuit

4‧‧‧Power amplification stage

41‧‧‧Audio power output stage

42‧‧‧Dynamic power supply voltage switch

421‧‧‧First power supply voltage input

422‧‧‧Second supply voltage input

423‧‧‧Power supply voltage output

5‧‧‧Drive output stage

51‧‧‧Stagnation time control circuit

52‧‧‧Voltage level shifting circuit

6‧‧‧Power supply circuit

61‧‧‧Amplitude and phase detection circuit

62‧‧‧Drive circuit

63‧‧‧Power supply output stage

631‧‧‧ input

632‧‧‧output

64‧‧‧reference voltage control circuit

65‧‧‧Error amplifier bandwidth control circuit

651‧‧‧ first input

652‧‧‧second input

653‧‧‧output

66‧‧‧voltage circuit

7‧‧‧Speakers

Claims (5)

A power amplifying device includes: a preamplifier stage; a preamplifier stage; and a bass boost control circuit connected to the preamplifier in a feedback manner; the bass boost control circuit is provided with a a first feedback resistor and an active capacitor multiplying circuit connected in parallel with the first feedback resistor; a power amplifier stage, wherein the power amplifier stage is provided with an audio power output stage and a dynamic power voltage switch, the audio power output The stage is electrically connected to the preamplifier stage, the dynamic power voltage switch has a first power voltage input terminal, a second power voltage input terminal and a power voltage output terminal, and the first power voltage input terminal is connected to a smaller one. a fixed power supply voltage, the power voltage output end is connected to the audio power output stage; a power supply circuit, the power supply circuit is provided with an amplitude and phase detection circuit, a drive circuit and a power supply output stage, the drive circuit includes a reference voltage control circuit, an error amplifier bandwidth control circuit, and a voltage dividing circuit, the error amplifier The wide control circuit has a first input end, a second input end and an output end, and the amplitude and phase detecting circuit are electrically connected to the preamplifier stage, the reference voltage control circuit and the second input end of the error amplifier bandwidth control circuit, respectively The reference voltage control circuit is also electrically connected to the first input end of the error amplifier bandwidth control circuit, and the output end of the error amplifier bandwidth control circuit is electrically connected to the input end of the power supply power output stage. The circuit is connected to the power supply output stage and its output terminal and error amplifier bandwidth control by feedback mode. The second input end of the circuit, the output end of the power supply output stage is also electrically connected to the second power voltage input end of the dynamic power voltage switch, for generating a dynamic power supply voltage with a larger fixed power supply voltage. The power amplifying device of claim 1, wherein the preamplifier is a fully differential amplifier. The power amplifying device of claim 1, wherein the bass boost control circuit is provided with a second feedback resistor connected in series with the active capacitor multiplying circuit, and the second feedback resistor is smaller than the first feedback resistance. The power amplifying device according to any one of claims 1 to 3, further comprising a driving output stage disposed between the preamplifier stage and the power amplifying stage, and the driving The output stages are respectively connected to the preamplifier stage and the power amplifier stage. The power amplifying device of claim 4, wherein the driving output stage is provided with a dead time control circuit and a voltage level shifting circuit electrically connected to the dead time control circuit, the dead time control circuit And the voltage level shifting circuit is electrically connected to the preamplifier of the preamplifier stage and the audio power output stage of the power amplifier stage.