單管音頻放大器

??單管音頻放大器

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01 單管放大器

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一、前言

??前天，對于英飛凌的模擬硅麥的信號進行了初步測，?硅麥輸出信號的峰峰值只有200mV，?所以在進行MCU信號采集之前需要10倍左右（20dB）的放大。

二、單管放大

??這是基于NPN晶體管BC547的音頻放大電路，?輸入1kHz的正弦波，峰峰值為20mV，這是測量T1集電極的放大后的波形。?通過數字萬用表交流檔測量輸入輸出交流信號的幅值，?可以計算出放大電路的放大倍數，?這個電路的放大倍數為63倍左右。?因此可以滿足對硅麥信號的放大要求。

▲ 圖1.2.1 單管音頻放大器

??這是利用數字信號源 DG1062產生50Hz至 50kHz的信號，測量放大電路的輸出信號幅值，便可以得到放大電路的幅頻特性。?整體上來看，放大器的帶寬超過10kHz 。?智能車競賽中所使用的導航聲音頻率范圍在250Hz到2000Hz，?可以看到單管放大器在這個范圍內的增益是穩定的。

▲ 圖1.2.2 放大器的幅頻特性

fset=[50.00,53.61,57.49,61.64,66.10,70.87,76.00,81.49,87.38,93.69,100.46,107.72,115.51,123.85,132.80,142.40,152.69,163.73,175.56,188.25,201.85,216.44,232.08,248.85,266.83,286.12,306.80,328.97,352.74,378.23,405.57,434.87,466.30,500.00,536.13,574.88,616.42,660.97,708.74,759.96,814.88,873.76,936.91,1004.62,1077.22,1155.06,1238.54,1328.04,1424.02,1526.93,1637.27,1755.60,1882.47,2018.51,2164.38,2320.79,2488.51,2668.35,2861.18,3067.95,3289.67,3527.40,3782.32,4055.65,4348.75,4663.02,5000.00,5361.34,5748.78,6164.23,6609.71,7087.37,7599.56,8148.75,8737.64,9369.09,10046.17,10772.17,11550.65,12385.38,13280.44,14240.18,15269.28,16372.75,17555.96,18824.68,20185.09,21643.81,23207.94,24885.12,26683.50,28611.84,30679.54,32896.66,35274.01,37823.17,40556.54,43487.45,46630.17,50000.00] out=[301.17,394.37,396.56,403.21,408.36,411.79,416.53,419.96,423.67,426.26,432.19,430.94,432.97,434.84,436.52,437.83,438.30,440.05,441.93,442.08,442.22,443.35,444.09,448.51,444.96,445.16,445.69,445.91,446.29,446.47,446.72,446.56,446.87,447.85,446.90,446.91,447.19,446.96,446.91,446.78,447.05,446.96,446.80,446.55,446.67,446.60,446.46,446.20,446.32,446.09,445.72,445.73,445.20,444.88,444.36,443.82,443.54,442.48,441.85,440.98,440.16,438.62,437.41,436.44,434.51,432.57,430.61,428.22,424.96,422.61,419.36,415.24,411.21,406.82,401.74,396.10,389.90,383.47,376.30,368.59,360.10,351.31,342.27,332.24,322.78,311.53,300.72,291.80,278.65,267.46,256.46,245.13,234.30,223.63,213.00,203.14,193.47,184.44,175.31,167.02] from headm import * from tsmodule.tsvisa import * from tsmodule.tsstm32 import *dg1062open(119)fset = exp(linspace(log(50), log(50000), 100)) out = []dg1062freq(1, fset[0]) time.sleep(2)for f in fset:dg1062freq(1,f)time.sleep(1.5)meter = meterval()out.append(meter[0]*1000.0)printf(meter)tspsave('freq', fset=fset, out=out)plt.loglog(fset, out)plt.xlabel("Frequency(Hz)") plt.ylabel("Out(mV)") plt.grid(True) plt.tight_layout() plt.show()

??現在看看放大器的輸出信號的動態范圍。?當信號過大，輸出信號具有一定的失真。

三、電路仿真

??利用LTspace對單管放大電路進行仿真，?利用輸入輸出的幅度，可以計算出電路的增益，?放大倍數為63.9倍，這與前面實際電路所得到的增益是一致的。

▲ 圖1.3.1 LTSpace仿真電路

▲ 圖1.3.2 輸入輸出波形

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※ 總??結 ※

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??本文測試了基于BC647的單管音頻放大電路，?該電路的增益超過60倍，?帶寬超過10kHz。

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■ 相關文獻鏈接:

• 單管音頻放大器

● 相關圖表鏈接:

• 圖1.2.1 單管音頻放大器
• 圖1.3.1 LTSpace仿真電路
• 圖1.3.2 輸入輸出波形

總結

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