AMP328音频放大器

需要在音频定位实验中有一个足够功率的音频功率放大器，这是一个在几年前购买得到的"傻瓜175”AMP328的音频放大器。可以在网络上得到它的帮助
。

下面对于它进行简单的测试，以便后面进行应用。

测试的AMP328 Audio Power Amplifier

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01基本测试

1. 输入阻抗

使用手持LCR表，测试输入阻抗为30k欧姆。

2. 输入相位

同个测量AMP328 的输入和输出波形，可以看到它们之间是同相位的。因此，在对它如果实施负反馈则需要借助于另外的反相放大器。

AMP328的输入和输出信号是同相的

3.增益测试

在输入施加29.1mV的正弦波，在输出可以得到3.1V的交流正弦波。它的增益大约为：$Gain=\frac{3.1}{29\times 10^{-3}}=106.9$。

4.静态功耗

在电源电压$\pm 12V$的时候，+12V的电源为2.5mA，-12V的电源50mA。

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02频率响应

使用 AD9833数字信号发生器模块 产生测试信号，经过电位器分压之后，生成大约50mV左右的交流电压施加在AMP328输入端。

使用FLUKE48，DM3068测量输入输出交流信号的电压。在 什么数字万用表可以测量噪声？ 博文中给出了这两款万用表测量交流信号的带宽都大于200kHz。所以用于测试AMP328模块幅频特性是没有问题的。

1.全频段增益测量

下面是测量的频率范围从10~30000Hz，共100个频率点的AMP328的交流增益曲线。测量结果显示，该音频功率放大器的高频截止频率（增益下降3db）大于30kHz。

^{▲ 0~30KHz频率响应}

^{▲ 测量过程输出波形的变化}

inv=[0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05]
outv=[2.96,5.15,5.16,5.17,5.17,5.17,5.17,5.17,5.17,5.17,5.17,5.17,5.16,5.16,5.16,5.16,5.16,5.16,5.16,5.16,5.16,5.16,5.16,5.15,5.15,5.15,5.15,5.15,5.15,5.15,5.15,5.14,5.14,5.14,5.14,5.14,5.14,5.14,5.13,5.13,5.13,5.13,5.13,5.13,5.13,5.13,5.12,5.12,5.12,5.11,5.11,5.10,5.10,5.10,5.09,5.09,5.09,5.09,5.09,5.10,5.10,5.10,5.10,5.10,5.10,5.10,5.09,5.09,5.09,5.09,5.08,5.08,5.07,5.07,5.06,5.06,5.05,5.04,5.04,5.03,5.02,5.01,5.00,4.99,4.97,4.96,4.95,4.93,4.92,4.91,4.89,4.88,4.87,4.86,4.85,4.85,4.84,4.83,4.83,4.82]
f=[10.00,312.93,615.86,918.79,1221.72,1524.65,1827.58,2130.51,2433.43,2736.36,3039.29,3342.22,3645.15,3948.08,4251.01,4553.94,4856.87,5159.80,5462.73,5765.66,6068.59,6371.52,6674.44,6977.37,7280.30,7583.23,7886.16,8189.09,8492.02,8794.95,9097.88,9400.81,9703.74,10006.67,10309.60,10612.53,10915.45,11218.38,11521.31,11824.24,12127.17,12430.10,12733.03,13035.96,13338.89,13641.82,13944.75,14247.68,14550.61,14853.54,15156.46,15459.39,15762.32,16065.25,16368.18,16671.11,16974.04,17276.97,17579.90,17882.83,18185.76,18488.69,18791.62,19094.55,19397.47,19700.40,20003.33,20306.26,20609.19,20912.12,21215.05,21517.98,21820.91,22123.84,22426.77,22729.70,23032.63,23335.56,23638.48,23941.41,24244.34,24547.27,24850.20,25153.13,25456.06,25758.99,26061.92,26364.85,26667.78,26970.71,27273.64,27576.57,27879.49,28182.42,28485.35,28788.28,29091.21,29394.14,29697.07,30000.00]

2.低频段增益测量

下面是测量5Hz~100Hz之间100个频率点的增益曲线。以增益下降3dB来看，该音频功率放大器的高通截止频率大约是15Hz左右。

^{▲ 5至100Hz功率放大器的增益曲线}

^{▲ 测量过程中功放输出波形}

inv=[0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05]
outv=[1.42,1.77,2.10,2.42,2.68,2.91,3.14,3.32,3.48,3.62,3.75,3.87,3.96,4.06,4.14,4.21,4.27,4.33,4.38,4.43,4.48,4.51,4.55,4.58,4.61,4.64,4.67,4.69,4.71,4.73,4.75,4.77,4.78,4.80,4.81,4.83,4.84,4.85,4.86,4.87,4.88,4.89,4.90,4.91,4.92,4.93,4.93,4.94,4.95,4.95,4.96,4.96,4.97,4.98,4.98,4.98,4.99,4.99,5.00,5.00,5.00,5.01,5.01,5.01,5.02,5.02,5.02,5.03,5.03,5.03,5.04,5.04,5.04,5.04,5.04,5.05,5.05,5.05,5.05,5.06,5.06,5.06,5.06,5.06,5.06,5.07,5.07,5.07,5.07,5.07,5.07,5.08,5.08,5.08,5.08,5.08,5.08,5.08,5.08,5.09]
f=[5.00,5.96,6.92,7.88,8.84,9.80,10.76,11.72,12.68,13.64,14.60,15.56,16.52,17.47,18.43,19.39,20.35,21.31,22.27,23.23,24.19,25.15,26.11,27.07,28.03,28.99,29.95,30.91,31.87,32.83,33.79,34.75,35.71,36.67,37.63,38.59,39.55,40.51,41.46,42.42,43.38,44.34,45.30,46.26,47.22,48.18,49.14,50.10,51.06,52.02,52.98,53.94,54.90,55.86,56.82,57.78,58.74,59.70,60.66,61.62,62.58,63.54,64.49,65.45,66.41,67.37,68.33,69.29,70.25,71.21,72.17,73.13,74.09,75.05,76.01,76.97,77.93,78.89,79.85,80.81,81.77,82.73,83.69,84.65,85.61,86.57,87.53,88.48,89.44,90.40,91.36,92.32,93.28,94.24,95.20,96.16,97.12,98.08,99.04,100.00]

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03结论

本文实验中对于音频功率放大模块AMP328的基本功能以及频率曲线进行了测量。这些数据支撑未来其它的实验。

^{▲ 测试所使用的面包板连接电路}