WO2020248769A1 - 一种音频功率放大器及其增益控制电路和控制方法 - Google Patents

一种音频功率放大器及其增益控制电路和控制方法 Download PDF

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WO2020248769A1
WO2020248769A1 PCT/CN2020/090777 CN2020090777W WO2020248769A1 WO 2020248769 A1 WO2020248769 A1 WO 2020248769A1 CN 2020090777 W CN2020090777 W CN 2020090777W WO 2020248769 A1 WO2020248769 A1 WO 2020248769A1
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audio signal
gain
digital audio
digital
analog
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PCT/CN2020/090777
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English (en)
French (fr)
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蒋松鹰
姚炜
周佳宁
程剑涛
杜黎明
孙洪军
乔永庆
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上海艾为电子技术股份有限公司
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Priority to KR1020227001086A priority Critical patent/KR20220034113A/ko
Publication of WO2020248769A1 publication Critical patent/WO2020248769A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/181—Low-frequency amplifiers, e.g. audio preamplifiers
    • H03F3/183—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers

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  • the invention relates to the technical field of audio power amplifiers, and more specifically, to an audio power amplifier and its gain control circuit and control method.
  • audio power amplifiers can not only extend the working time of electronic devices, reduce the heat generation of electronic devices, but also can obtain larger volume and better sound quality, audio power amplifiers have gained popularity in the field of electronic devices such as mobile phones. Wide range of applications.
  • Audio power amplifiers are mainly divided into two categories, one is analog audio power amplifier, and the other is digital audio power amplifier. Since the audio signal can be transmitted through the digital audio power amplifier, it has extremely high anti-radio frequency interference performance and low noise floor. Therefore, the current digital audio power amplifier is widely used. However, in the application scenario of the two-in-one earpiece and earphone, it is necessary to further reduce the noise floor of the power amplifier while ensuring the total gain (digital plus analog gain) of the small signal amplification is unchanged.
  • the present invention provides an audio power amplifier and its gain control circuit and control method to further reduce the noise floor of the power amplifier while ensuring that the total gain of small signal amplification remains unchanged.
  • a gain control circuit is applied to an audio power amplifier.
  • the audio power amplifier includes a digital-to-analog converter and an analog amplifier connected to the digital-to-analog converter.
  • the gain control circuit includes a signal threshold detection unit, a gain compensation unit and Delay control unit;
  • the signal threshold detection unit is configured to perform threshold detection on the digital audio signal at the input of the digital-to-analog converter to obtain the threshold level of the digital audio signal;
  • the gain compensation unit is used to determine the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and adjust the gain of the digital audio signal to the original value when the digital audio signal crosses zero. N times of, the adjusted digital audio signal is transmitted to the digital-to-analog converter, and the digital-to-analog converter converts the adjusted digital audio signal into an analog audio signal, and transmits the analog audio signal to the Analog amplifier
  • the delay control unit is used to adjust the gain of the analog amplifier to the original 1/N when the analog audio signal is transmitted to the analog amplifier, and N is a natural number greater than 1.
  • the threshold level includes level 1 to level M, wherein the amplitude of the signal at level i+1 is smaller than the amplitude of the signal at level i, and the adjustment multiple of level i+1 is N i+ 1 is greater than the i-th stage to adjust multiple N i, 1 ⁇ i ⁇ i + 1 ⁇ M , M is a natural number greater than 1.
  • N 2j, and 1 ⁇ j ⁇ M.
  • N is an integer multiple of j.
  • the signal threshold detection unit obtains the threshold level of the digital audio signal by comparing the amplitude of the digital audio signal at the input of the digital-to-analog converter with the upper limit value and the lower limit value of the threshold level .
  • the gain compensation unit includes a determination module, a zero-crossing detection module, and a compensation module;
  • the determining module is configured to determine the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal;
  • the zero-crossing detection module is used to detect whether the digital audio signal crosses zero
  • the compensation module is used to adjust the gain of the digital audio signal to N times the original when the digital audio signal crosses zero.
  • the gain compensation unit is further configured to, after determining the gain adjustment multiple N of the digital audio signal, transmit the gain adjustment multiple N to the delay control unit, so that the delay control unit is The gain adjustment factor N determines the gain adjustment factor 1/N of the analog amplifier;
  • the delay control unit is further configured to determine whether the analog audio signal is transmitted to the analog amplifier after determining the gain adjustment multiple 1/N of the analog amplifier, and if so, adjust the gain of the analog amplifier to the original 1/N.
  • a gain control method applied to the gain control circuit as described in any one of the above, the gain control method includes:
  • the signal threshold detection unit performs threshold detection on the digital audio signal at the input of the digital-to-analog converter to obtain the threshold level of the digital audio signal;
  • the gain compensation unit determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and adjusts the gain of the digital audio signal to the original N times when the digital audio signal crosses zero, And transmit the adjusted digital audio signal to the digital-to-analog converter, so that the digital-to-analog converter converts the adjusted digital audio signal into an analog audio signal, and transmits the analog audio signal to the analog Amplifier
  • the delay control unit adjusts the gain of the analog amplifier to the original 1/N, where N is a natural number greater than 1.
  • the threshold level includes level 1 to level M, wherein the amplitude of the signal at level i+1 is smaller than the amplitude of the signal at level i, and the adjustment multiple of level i+1 is N i+ 1 is greater than the i-th stage to adjust multiple N i, 1 ⁇ i ⁇ i + 1 ⁇ M , M is a natural number greater than 1.
  • N 2j, and 1 ⁇ j ⁇ M.
  • N is an integer multiple of j.
  • the signal threshold detection unit performs threshold detection on the digital audio signal at the input of the digital-to-analog converter, and obtaining the threshold level of the digital audio signal includes:
  • the signal threshold detection unit obtains the threshold level of the digital audio signal by comparing the amplitude of the digital audio signal at the input end of the digital-to-analog converter with the upper limit value and the lower limit value of the threshold level.
  • the gain compensation unit includes a determination module, a zero-crossing detection module, and a compensation module.
  • the gain compensation unit determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and sets the When the audio signal crosses zero, adjusting the gain of the digital audio signal to N times the original includes:
  • the determining module determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal
  • the zero-crossing detection module detects whether the digital audio signal crosses zero
  • the compensation module adjusts the gain of the digital audio signal to N times the original.
  • the method further includes:
  • the gain compensation unit transmits the gain adjustment multiple N to the delay control unit, so that the delay control unit determines the gain adjustment multiple 1/N of the analog amplifier according to the gain adjustment multiple N;
  • the delay control unit After determining the gain adjustment multiple 1/N of the analog amplifier, the delay control unit determines whether the analog audio signal is transmitted to the analog amplifier, and if so, adjusts the gain of the analog amplifier to the original 1/N .
  • An audio power amplifier includes a digital-to-analog converter, an analog amplifier connected to the digital-to-analog converter, and the gain control circuit described in any one of the above.
  • the delay control unit adjusts the gain of the analog amplifier to the original 1/N when the signal is transmitted to the analog amplifier, so that the synchronization of the digital gain adjustment and the analog gain adjustment is ensured, so that the It will cause signal distortion and avoid pop sound and noise.
  • FIG. 1 is a schematic structural diagram of a gain control circuit provided by an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of an audio power amplifier provided by an embodiment of the present invention.
  • Fig. 3 is a flowchart of a gain control method provided by an embodiment of the present invention.
  • the embodiment of the present invention provides a gain control circuit, which is applied to a digital audio power amplifier.
  • the digital audio power amplifier includes a digital-to-analog converter 1 and an analog signal transmission link of the digital-to-analog converter 1
  • the amplifier 2 includes a digital-to-analog converter 1 and an analog amplifier 2 connected to the digital-to-analog converter 1.
  • the gain control circuit includes a signal threshold detection unit 3, a gain compensation unit 4 and a delay control unit 5.
  • the signal threshold detection unit 3 is used to perform threshold detection on the digital audio signal at the input of the digital-to-analog converter 1 to obtain the threshold level of the digital audio signal;
  • the gain compensation unit 4 is used to determine the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and adjust the gain of the digital audio signal to the original N times when the digital audio signal crosses zero, and adjust the adjusted
  • the digital audio signal is transmitted to the digital-to-analog converter 1, so that the digital-to-analog converter 1 converts the adjusted digital audio signal into an analog audio signal, and transmits the analog audio signal to the analog amplifier 2;
  • the delay control unit 5 is used to adjust the gain of the analog amplifier 2 to the original 1/N when the analog audio signal is transmitted to the analog amplifier 2, and N is a natural number greater than 1.
  • the delay control unit 5 is connected to the gain compensation unit 4. After the gain compensation unit 4 determines the gain adjustment multiple N of the digital audio signal, it transmits the gain adjustment multiple N to the delay control unit 5. , So that the delay control unit 5 obtains the gain adjustment multiple of the analog amplifier 2 as 1/N.
  • the delay control unit 5 adjusts the gain of the analog amplifier 2 to the original 1/N when the analog audio signal is transmitted to the analog amplifier 2, the synchronization of the digital gain adjustment and the analog gain adjustment is ensured, so that It causes signal distortion and avoids pop sound and noise.
  • the threshold level includes level 1 to level M, the amplitude of the i+1 level signal is less than the amplitude of the i level signal, and the adjustment multiple Ni +1 of the i+1 level is greater than the adjustment multiple of the i level N i , 1 ⁇ i ⁇ i+1 ⁇ M, and M is a natural number greater than 1.
  • the signal threshold detection unit 3 obtains the threshold level of the digital audio signal by comparing the amplitude of the digital audio signal at the input of the digital-to-analog converter 1 with the upper limit and the lower limit of at least one threshold level. .
  • the signal threshold detection unit 3 compares the amplitude of the digital audio signal with the first-level threshold.
  • the threshold includes an upper limit and a lower limit, and the amplitude of the digital audio signal is compared. After comparing the value with the upper limit and lower limit of the first level, if the amplitude of the digital audio signal is between the lower limit and the upper limit of the first level, then the threshold level of the digital audio signal is the first In level 1, if the amplitude of the digital audio signal is less than the lower limit of level 1, the amplitude of the digital audio signal is compared with the threshold of level 2, and so on. If the amplitude of the digital audio signal is greater than the upper limit of the first stage, it means that the digital audio signal is not a small signal and is not within the gain adjustment range of the present invention, and no gain adjustment is performed on the digital audio signal.
  • N 2j, and 1 ⁇ j ⁇ M.
  • N is an integer multiple of j.
  • the threshold level of the digital audio signal is determined to be level 1
  • the gain adjustment multiple of the digital audio signal is 2
  • the gain adjustment multiple of the analog amplifier 2 is 1/2
  • the gain adjustment factor of the digital audio signal is 4
  • the gain adjustment factor of the analog amplifier 2 is 1/4, and so on, and will not be repeated here.
  • N may also be equal to 3j, 4j, 5j... etc.
  • the gain compensation unit 4 in the embodiment of the present invention includes a determination module, a zero-crossing detection module, and a compensation module.
  • the determination module is used to determine the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and zero-crossing
  • the detection module is used to detect whether the digital audio signal crosses zero
  • the compensation module is used to adjust the gain of the digital audio signal to N times when the digital audio signal crosses zero, so as to avoid the shortcomings of premature change of the audio.
  • the gain compensation unit 4 is also used to transmit the gain adjustment factor N to the delay control unit 5 after determining the gain adjustment factor N of the digital audio signal, so that the delay control unit 5 is based on the gain
  • the adjustment factor N determines the gain adjustment factor 1/N of the analog amplifier
  • the delay control unit 5 is also used to determine whether the analog audio signal is transmitted to the analog amplifier 2 after determining the gain adjustment multiple 1/N of the analog amplifier 2, and if so, adjust the gain of the analog amplifier to the original 1/N.
  • the gain of the digital audio signal or the analog amplifier 2 can be adjusted by adjusting the amplification factor of the signal amplifying circuit, etc., which will not be repeated here.
  • the embodiment of the present invention also provides a gain control method, which is applied to the gain control circuit provided in any of the above embodiments. As shown in FIG. 3, the gain control method includes:
  • the signal threshold detection unit performs threshold detection on the digital audio signal at the input of the digital-to-analog converter to obtain the threshold level of the digital audio signal;
  • the threshold level includes level 1 to level M, the amplitude of the i+1 level signal is less than the amplitude of the i level signal, and the adjustment multiple Ni +1 of the i+1 level is greater than the adjustment multiple of the i level N i , 1 ⁇ i ⁇ i+1 ⁇ M, and M is a natural number greater than 1.
  • the signal threshold detection unit 3 compares the amplitude of the digital audio signal with the first-level threshold.
  • the threshold includes an upper limit and a lower limit, and the amplitude of the digital audio signal is compared. After comparing the value with the upper limit and lower limit of the first level, if the amplitude of the digital audio signal is between the lower limit and the upper limit of the first level, then the threshold level of the digital audio signal is the first In level 1, if the amplitude of the digital audio signal is less than the lower limit of level 1, the amplitude of the digital audio signal is compared with the threshold of level 2, and so on. If the amplitude of the digital audio signal is greater than the upper limit of the first stage, it means that the digital audio signal is not a small signal and is not within the gain adjustment range of the present invention, and no gain adjustment is performed on the digital audio signal.
  • the gain compensation unit determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and adjusts the gain of the digital audio signal to the original N when the digital audio signal crosses zero. And transmitting the adjusted digital audio signal to the digital-to-analog converter;
  • the gain compensation unit 4 includes a determination module, a zero-crossing detection module, and a compensation module.
  • the gain compensation unit determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal, and when the digital audio signal crosses zero, it will Adjusting the gain of the digital audio signal to N times the original includes:
  • the determining module determines the gain adjustment multiple N of the digital audio signal according to the threshold level of the digital audio signal
  • the zero-crossing detection module detects whether the digital audio signal crosses zero
  • the compensation module adjusts the gain of the digital audio signal to N times the original.
  • the delay control unit adjusts the gain of the analog amplifier to the original 1/N, where N is a natural number greater than 1.
  • the gain compensation unit transmits the gain adjustment multiple N to the delay control unit so that the delay control unit determines the gain adjustment multiple 1/N of the analog amplifier according to the gain adjustment multiple N.
  • the delay control unit can determine whether the analog audio signal output by the digital-to-analog converter is transmitted to the analog amplifier according to the preset delay time, and can also determine the output of the digital-to-analog converter based on the signal amplitude detected in real time. Whether the analog audio signal is transmitted to the analog amplifier, the present invention does not limit this.
  • N 2j, and 1 ⁇ j ⁇ M.
  • N is an integer multiple of j.
  • the threshold level of the digital audio signal is determined to be level 1
  • the gain adjustment multiple of the digital audio signal is 2
  • the gain adjustment multiple of the analog amplifier is 1/2
  • the gain adjustment factor of the digital audio signal is 4
  • the gain adjustment factor of the analog amplifier is 1/4, and so on, and will not be repeated here.
  • N may also be equal to 3j, 4j, 5j... etc.
  • the embodiment of the present invention also provides an audio power amplifier, as shown in FIG. 1, comprising a digital-to-analog converter 1, an analog amplifier 2 located on the signal transmission link of the digital-to-analog converter 1, and the gain provided by any of the above embodiments Control circuit.
  • the signal transmission link of the digital-to-analog converter 1, that is, between the digital-to-analog converter 1 and the analog amplifier 2 also includes the analog audio transmitted from the digital-to-analog converter 1 to the analog amplifier 2.
  • the PWM modulation unit 6 for PWM modulation of the signal, etc., will not be repeated here.
  • the gain of the analog amplifier can be adjusted without changing the total gain of the amplifier. , Reduce the bottom noise of the audio power amplifier.
  • the delay control unit adjusts the gain of the analog amplifier to the original 1/N when the signal is transmitted to the analog amplifier, the synchronization of the digital gain adjustment and the analog gain adjustment is ensured, so that the It will cause signal distortion and avoid pop sound and noise.

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Abstract

一种音频功率放大器及其增益控制电路和控制方法，包括信号阈值检测单元（3）、增益补偿单元（4）和延迟控制单元（5）；信号阈值检测单元（3）用于对数模转换器（1）输入端的数字音频信号进行阈值检测，获得数字音频信号的阈值级别；增益补偿单元（4）用于根据数字音频信号的阈值级别确定数字音频信号的增益调整倍数N，并在数字音频信号过零时，将数字音频信号的增益调整为原来的N倍，将调整后的数字音频信号传输至数模转换器（1）；延迟控制单元（5）用于在信号传输至模拟放大器（2）时，将模拟放大器（2）的增益调整为原来的1/N，N为大于1的自然数。由于N*(1/N)＝1，因此，可以在保证放大总增益不变的情况下，通过调整模拟放大器的增益，减小音频功率放大器的底噪。

Description

一种音频功率放大器及其增益控制电路和控制方法
本申请要求于2019年6月12日提交中国专利局、申请号为201910506445.X、发明名称为“一种音频功率放大器及其增益控制电路和控制方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及音频功放技术领域，更具体地说，涉及一种音频功率放大器及其增益控制电路和控制方法。
背景技术
由于高效率的音频功率放大器不仅能够延长电子设备的工作时间、减小电子设备的发热量，而且能够获得更大的音量和更好的音质，因此，音频功率放大器在手机等电子设备领域得到了广泛的应用。
音频功率放大器主要分两类，一类为模拟音频功率放大器，另一类为数字音频功率放大器。由于音频信号能够通过数字音频功率放大器进行数字信号传输，具有极高的抗射频干扰性能和较低的底噪，因此，目前数字音频功率放大器的应用较为广泛。但是，在听筒耳机二合一的应用场景下，需要在保证小信号的放大总增益(数字加模拟增益)不变的情况下，进一步减小功率放大器的底噪。
发明内容
有鉴于此，本发明提供了一种音频功率放大器及其增益控制电路和控制方法，以在保证小信号的放大总增益不变的情况下，进一步减小功率放大器的底噪。
为实现上述目的，本发明提供如下技术方案：
一种增益控制电路，应用于音频功率放大器，所述音频功率放大器包括数 模转换器和与所述数模转换器相连的模拟放大器，所述增益控制电路包括信号阈值检测单元、增益补偿单元和延迟控制单元；
所述信号阈值检测单元用于对所述数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别；
所述增益补偿单元用于根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍，将调整后的数字音频信号传输至所述数模转换器，所述数模转换器将调整后的数字音频信号转换为模拟音频信号，并将所述模拟音频信号传输至所述模拟放大器；
所述延迟控制单元用于在所述模拟音频信号传输至所述模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，N为大于1的自然数。
可选地，所述阈值级别包括第1级至第M级，其中，第i+1级的信号的幅值小于第i级的信号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
可选地，当所述数字音频信号的阈值级别为j时，N＝2j，1≤j≤M。
可选地，N为j的整数倍。
可选地，所述信号阈值检测单元通过将所述数模转换器输入端的数字音频信号的幅值与阈值级别的上限值和下限值进行对比，来获得所述数字音频信号的阈值级别。
可选地，所述增益补偿单元包括确定模块、过零检测模块和补偿模块；
所述确定模块用于根据所述数字音频信号的阈值级别，确定所述数字音频信号的增益调整倍数N；
所述过零检测模块用于检测所述数字音频信号是否过零；
所述补偿模块用于在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍。
可选地，所述增益补偿单元还用于在确定所述数字音频信号的增益调整倍数N后，将所述增益调整倍数N传输至所述延迟控制单元，以使所述延迟控 制单元根据所述增益调整倍数N确定所述模拟放大器的增益调整倍数1/N；
所述延迟控制单元还用于在确定所述模拟放大器的增益调整倍数1/N后，判断所述模拟音频信号是否传输至所述模拟放大器，若是，将所述模拟放大器的增益调整为原来的1/N。
一种增益控制方法，应用于如上任一项所述的增益控制电路，所述增益控制方法包括：
信号阈值检测单元对数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别；
增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍，并将调整后的数字音频信号传输至所述数模转换器，以使所述数模转换器将调整后的数字音频信号转换为模拟音频信号，并将所述模拟音频信号传输至所述模拟放大器；
延迟控制单元在所述模拟音频信号传输至模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，N为大于1的自然数。
可选地，所述阈值级别包括第1级至第M级，其中，第i+1级的信号的幅值小于第i级的信号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
可选地，当所述数字音频信号的阈值级别为j时，N＝2j，1≤j≤M。
可选地，N为j的整数倍。
可选地，信号阈值检测单元对数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别包括：
信号阈值检测单元通过将所述数模转换器输入端的数字音频信号的幅值与阈值级别的上限值和下限值进行对比，来获得所述数字音频信号的阈值级别。
可选地，所述增益补偿单元包括确定模块、过零检测模块和补偿模块，增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益 调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍包括：
所述确定模块根据所述数字音频信号的阈值级别，确定所述数字音频信号的增益调整倍数N；
所述过零检测模块检测所述数字音频信号是否过零；
当所述数字音频信号过零时，所述补偿模块将所述数字音频信号的增益调整为原来的N倍。
可选地，增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N之后，还包括：
所述增益补偿单元将所述增益调整倍数N传输至所述延迟控制单元，以使所述延迟控制单元根据所述增益调整倍数N确定所述模拟放大器的增益调整倍数1/N；
所述延迟控制单元在确定所述模拟放大器的增益调整倍数1/N后，判断所述模拟音频信号是否传输至所述模拟放大器，若是，将所述模拟放大器的增益调整为原来的1/N。
一种音频功率放大器，包括数模转换器、与所述数模转换器相连的模拟放大器、如上任一项所述的增益控制电路。
与现有技术相比，本发明所提供的技术方案具有以下优点：
本发明所提供的音频功率放大器及其增益控制电路和控制方法，由于N*(1/N)＝1，因此，可以在保证放大总增益不变的情况下，通过调整模拟放大器的增益，减小音频功率放大器的底噪。并且，由于延迟控制单元是在所述信号传输至所述模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，因此，保证了数字增益调整和模拟增益调整的同步，从而不会引起信号的畸变，避免了pop音和杂音等的出现。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1为本发明实施例提供的一种增益控制电路的结构示意图；
图2为本发明实施例提供的一种音频功率放大器的结构示意图；
图3为本发明实施例提供的一种增益控制方法的流程图。
具体实施方式
为使本发明的上述目的、特征和优点能够更加明显易懂，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明实施例提供了一种增益控制电路，应用于数字音频功率放大器，如图1所示，该数字音频功率放大器包括数模转换器1和位于数模转换器1信号传输链路上的模拟放大器2，即包括数模转换器1和与数模转换器1相连的模拟放大器2，该增益控制电路包括信号阈值检测单元3、增益补偿单元4和延迟控制单元5。
其中，信号阈值检测单元3用于对数模转换器1输入端的数字音频信号进行阈值检测，获得数字音频信号的阈值级别；
增益补偿单元4用于根据数字音频信号的阈值级别确定数字音频信号的增益调整倍数N，并在数字音频信号过零时，将数字音频信号的增益调整为原来的N倍，并将调整后的数字音频信号传输至数模转换器1，以使得数模转换器1将调整后的数字音频信号转换为模拟音频信号，并将模拟音频信号传输至模拟放大器2；
延迟控制单元5用于在所述模拟音频信号传输至模拟放大器2时，将模拟 放大器2的增益调整为原来的1/N，N为大于1的自然数。
需要说明的是，本发明实施例中，延迟控制单元5与增益补偿单元4相连，当增益补偿单元4确定数字音频信号的增益调整倍数N之后，会将增益调整倍数N传输至延迟控制单元5，以便延迟控制单元5获得模拟放大器2的增益调整倍数为1/N。
由于N*(1/N)＝1，即数字增益和模拟增益的总放大倍数为1，因此，可以保证信号的放大总增益不变，从而可以在保证放大总增益不变的情况下，通过分级调整模拟放大器2的增益，减小音频功率放大器的底噪。并且，由于延迟控制单元5是在模拟音频信号传输至模拟放大器2时，将模拟放大器2的增益调整为原来的1/N，因此，保证了数字增益调整和模拟增益调整的同步，从而不会引起信号的畸变，避免了pop音和杂音等的出现。
其中，阈值级别包括第1级至第M级，第i+1级信号的幅值小于第i级信号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
本发明实施例中，信号阈值检测单元3通过将数模转换器1输入端的数字音频信号的幅值与至少一个阈值级别的上限值和下限值进行对比，来获得数字音频信号的阈值级别。
具体地，信号阈值检测单元3对数字音频信号进行阈值检测时，将数字音频信号的幅值与第1级的阈值进行对比，该阈值包括上限值和下限值，将数字音频信号的幅值与第1级的上限值和下限值分别进行对比后，如果数字音频信号的幅值在第1级的下限值和上限值之间，则该数字音频信号的阈值级别为第1级，如果数字音频信号的幅值小于第1级的下限值，则将数字音频信号的幅值与第2级的阈值进行对比，以此类推。如果数字音频信号的幅值大于第1级的上限值，则说明数字音频信号不属于小信号，不在本发明的增益调整范围内，不对该数字音频信号进行增益调整。
可选地，当数字音频信号的阈值级别为j时，N＝2j，1≤j≤M。可选地，N为j的整数倍。
以j＝1为例，当确定数字音频信号的阈值级别为第1级时，数字音频信号的增益调整倍数为2，模拟放大器2的增益调整倍数为1/2；当确定数字音频信号的阈值级别为第2级时，数字音频信号的增益调整倍数为4，模拟放大器2的增益调整倍数为1/4，以此类推，在此不再赘述。
当然，本发明并不仅限于此，在其他实施例中，N还可以等于3j、4j、5j…等。
可选地，本发明实施例中的增益补偿单元4包括确定模块、过零检测模块和补偿模块，确定模块用于根据数字音频信号的阈值级别，确定数字音频信号的增益调整倍数N，过零检测模块用于检测数字音频信号是否过零，补偿模块用于在数字音频信号过零时，将数字音频信号的增益调整为原来的N倍，以避免音频出现过早变声等缺点。
需要说明的是，本发明实施例中，增益补偿单元4还用于在确定数字音频信号的增益调整倍数N后，将增益调整倍数N传输至延迟控制单元5，以使延迟控制单元5根据增益调整倍数N确定模拟放大器的增益调整倍数1/N；
延迟控制单元5还用于在确定模拟放大器2的增益调整倍数1/N后，判断模拟音频信号是否传输至模拟放大器2，若是，将模拟放大器的增益调整为原来的1/N。
需要说明的是，如图2所示，在数模转换器1的信号传输链路上，即在数模转换器1和模拟放大器2之间还包括对数模转换器1传输至模拟放大器2的模拟音频信号进行PWM调制的PWM调制单元6等，在此不再赘述。还需要说明的是，本发明实施例中可以通过对信号放大电路的放大倍数进行调整等方式，对数字音频信号或模拟放大器2的增益进行调整，在此不再赘述。
本发明实施例还提供了一种增益控制方法，应用于如上任一实施例提供的增益控制电路，如图3所示，所述增益控制方法包括：
S101：信号阈值检测单元对数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别；
其中，阈值级别包括第1级至第M级，第i+1级信号的幅值小于第i级信 号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
具体地，信号阈值检测单元3对数字音频信号进行阈值检测时，将数字音频信号的幅值与第1级的阈值进行对比，该阈值包括上限值和下限值，将数字音频信号的幅值与第1级的上限值和下限值分别进行对比后，如果数字音频信号的幅值在第1级的下限值和上限值之间，则该数字音频信号的阈值级别为第1级，如果数字音频信号的幅值小于第1级的下限值，则将数字音频信号的幅值与第2级的阈值进行对比，以此类推。如果数字音频信号的幅值大于第1级的上限值，则说明数字音频信号不属于小信号，不在本发明的增益调整范围内，不对该数字音频信号进行增益调整。
S102：增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍，并将调整后的数字音频信号传输至所述数模转换器；
可选地，增益补偿单元4包括确定模块、过零检测模块和补偿模块，增益补偿单元根据数字音频信号的阈值级别确定数字音频信号的增益调整倍数N，并在数字音频信号过零时，将数字音频信号的增益调整为原来的N倍包括：
确定模块根据数字音频信号的阈值级别，确定数字音频信号的增益调整倍数N；
过零检测模块检测数字音频信号是否过零；
当数字音频信号过零时，补偿模块将数字音频信号的增益调整为原来的N倍。
S103：延迟控制单元在所述信号传输至模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，N为大于1的自然数。
需要说明的是，增益补偿单元得到增益调整倍数N后，会将增益调整倍数N传输至延迟控制单元，以使延迟控制单元根据增益调整倍数N确定模拟放大器的增益调整倍数1/N。
还需要说明的是，延迟控制单元可以根据预设的延迟时间，判断数模转换器输出的模拟音频信号是否传输至模拟放大器，也可以通过实时检测的信号幅值等，判断数模转换器输出的模拟音频信号是否传输至模拟放大器，本发明并不对此进行限定。
可选地，当数字音频信号的阈值级别为j时，N＝2j，1≤j≤M。可选地，N为j的整数倍。
以j＝1为例，当确定数字音频信号的阈值级别为第1级时，数字音频信号的增益调整倍数为2，模拟放大器的增益调整倍数为1/2；当确定数字音频信号的阈值级别为第2级时，数字音频信号的增益调整倍数为4，模拟放大器的增益调整倍数为1/4，以此类推，在此不再赘述。
当然，本发明并不仅限于此，在其他实施例中，N还可以等于3j、4j、5j…等。
本发明实施例还提供了一种音频功率放大器，如图1所示，包括数模转换器1、位于数模转换器1信号传输链路上的模拟放大器2以及如上任一实施例提供的增益控制电路。
当然，如图2所示，在数模转换器1的信号传输链路上，即在数模转换器1和模拟放大器2之间还包括对数模转换器1传输至模拟放大器2的模拟音频信号进行PWM调制的PWM调制单元6等，在此不再赘述。
本发明实施例所提供的音频功率放大器及其增益控制电路和控制方法，由于N*(1/N)＝1，因此，可以在保证放大总增益不变的情况下，通过调整模拟放大器的增益，减小音频功率放大器的底噪。并且，由于延迟控制单元是在所述信号传输至所述模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，因此，保证了数字增益调整和模拟增益调整的同步，从而不会引起信号的畸变，避免了pop音和杂音等的出现。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于 实施例公开的装置而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (15)

  1. 一种增益控制电路，应用于音频功率放大器，所述音频功率放大器包括数模转换器和与所述数模转换器相连的模拟放大器，其特征在于，所述增益控制电路包括信号阈值检测单元、增益补偿单元和延迟控制单元；
    所述信号阈值检测单元用于对所述数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别；
    所述增益补偿单元用于根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍，将调整后的数字音频信号传输至所述数模转换器，以使得所述数模转换器将调整后的数字音频信号转换为模拟音频信号，并将所述模拟音频信号传输至所述模拟放大器；
    所述延迟控制单元用于在所述模拟音频信号传输至所述模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，N为大于1的自然数。
  2. 根据权利要求1所述的增益控制电路，其特征在于，所述阈值级别包括第1级至第M级，其中，第i+1级的信号的幅值小于第i级的信号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
  3. 根据权利要求2所述的增益控制电路，其特征在于，当所述数字音频信号的阈值级别为j时，N＝2j，1≤j≤M。
  4. 根据权利要求3所述的增益控制电路，其特征在于，N为j的整数倍。
  5. 根据权利要求1所述的增益控制电路，其特征在于，所述信号阈值检测单元通过将所述数模转换器输入端的数字音频信号的幅值与至少一个阈值级别的上限值和下限值进行对比，来获得所述数字音频信号的阈值级别。
  6. 根据权利要求1所述的增益控制电路，其特征在于，所述增益补偿单元包括确定模块、过零检测模块和补偿模块；
    所述确定模块用于根据所述数字音频信号的阈值级别，确定所述数字音频信号的增益调整倍数N；
    所述过零检测模块用于检测所述数字音频信号是否过零；
    所述补偿模块用于在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍。
  7. 根据权利要求1所述的增益控制电路，其特征在于，所述增益补偿单元还用于在确定所述数字音频信号的增益调整倍数N后，将所述增益调整倍数N传输至所述延迟控制单元，以使所述延迟控制单元根据所述增益调整倍数N确定所述模拟放大器的增益调整倍数1/N；
    所述延迟控制单元还用于在确定所述模拟放大器的增益调整倍数1/N后，判断所述模拟音频信号是否传输至所述模拟放大器，若是，将所述模拟放大器的增益调整为原来的1/N。
  8. 一种增益控制方法，其特征在于，应用于增益控制电路，所述增益控制电路包括信号阈值检测单元、增益补偿单元和延迟控制单元，所述增益控制方法包括：
    信号阈值检测单元对数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别；
    增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍，并将调整后的数字音频信号传输至所述数模转换器，以使所述数模转换器将调整后的数字音频信号转换为模拟音频信号，并将所述模拟音频信号传输至所述模拟放大器；
    延迟控制单元在所述模拟音频信号传输至模拟放大器时，将所述模拟放大器的增益调整为原来的1/N，N为大于1的自然数。
  9. 根据权利要求8所述的增益控制方法，其特征在于，所述阈值级别包括第1级至第M级，其中，第i+1级的信号的幅值小于第i级的信号的幅值，第i+1级的调整倍数N i+1大于第i级的调整倍数N i，1≤i＜i+1≤M，M为大于1的自然数。
  10. 根据权利要求9所述的增益控制方法，其特征在于，当所述数字音频 信号的阈值级别为j时，N＝2j，1≤j≤M。
  11. 根据权利要求10所述的增益控制方法，其特征在于，N为j的整数倍。
  12. 根据权利要求8所述的增益控制方法，其特征在于，信号阈值检测单元对数模转换器输入端的数字音频信号进行阈值检测，获得所述数字音频信号的阈值级别包括：
    信号阈值检测单元通过将所述数模转换器输入端的数字音频信号的幅值与至少一个阈值级别的上限值和下限值进行对比，来获得所述数字音频信号的阈值级别。
  13. 根据权利要求8所述的增益控制方法，其特征在于，所述增益补偿单元包括确定模块、过零检测模块和补偿模块，增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N，并在所述数字音频信号过零时，将所述数字音频信号的增益调整为原来的N倍包括：
    所述确定模块根据所述数字音频信号的阈值级别，确定所述数字音频信号的增益调整倍数N；
    所述过零检测模块检测所述数字音频信号是否过零；
    当所述数字音频信号过零时，所述补偿模块将所述数字音频信号的增益调整为原来的N倍。
  14. 根据权利要求8所述的增益控制方法，其特征在于，增益补偿单元根据所述数字音频信号的阈值级别确定所述数字音频信号的增益调整倍数N之后，还包括：
    所述增益补偿单元将所述增益调整倍数N传输至所述延迟控制单元，以使所述延迟控制单元根据所述增益调整倍数N确定所述模拟放大器的增益调整倍数1/N；
    所述延迟控制单元在确定所述模拟放大器的增益调整倍数1/N后，判断所述模拟音频信号是否传输至所述模拟放大器，若是，将所述模拟放大器的增益调整为原来的1/N。
  15. 一种音频功率放大器，其特征在于，包括数模转换器、与所述数模转换器相连的模拟放大器、权利要求1～7任一项所述的增益控制电路。
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