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1、设计指标：Av250, 7?i10kQ, RL=5.lkQ, BW=50Hz50kHz, D5%。设计条件：输入信号（正弦信号）：2mVS%S5mV,信号源内阻：&=50。，电源电压：Vcc=12V；半导体三极管 9013,参数：4=100, Fbb=300Q, O=5pF,-=150MHz, 3VVcc20V, PcM=625mW, /cM=500mA, V（br）ceo=40V。1 .电路选型：小信号放大电路选用如图1所示两级阻容耦合放大电路，偏置电路采用射极偏置方 式，为了提高输入电阻及减小失真，满足失真度D0.12VT2级静态工作点确定:一般应取小汨 Yzeq2 Yzeqi选：Icm=
2、 1,2mA , /RO9= 0.012mA , VCFO9 = 4V3VL-Q2707。匕 QN5 .偏置电路设计计算（设Keq=07V）1级偏置电路计算:WRbl =10/BQ1 =10x0.007 = 0.07mA% =4x12 = 4VI 33故：7?bl =% =心=114.2861。取标称值 120 kQbl /bl 0.07% = /bl2/?bI = 0.072 x 120 = 0.588mW-W 选 120kQ Jw88= BQ1 = - = 63.492kQ 取标称值 62 kQ/Rb?，Rhi /rch0.07 0.007 0.063KDZKdI bqi选 62 kQ/-
3、W84b2 =后&2 = 0 0632 x 62 = 0.246mW - W8BQi BEQI _ Kq1 KeQI _ 4 0.7EQI(1 + )/bqi101x0.07 0.707=4oi2r =0.7072x0.3 = 0.15mW-WIxC 11 C1P , =/ ?/? , =0.7072 x 4.7 = 2.15mWiwKC1CQZ C1g选& 300Q/-W选尺/4.3koJw88=匕 c=匕 c%eq（Kqeqi）= 12-2-4 + 0.7 = 9,57 k。，CQ1取标称值9.lkQci = Qici =0.72x9.1 = 4.46mW|w 选跖 9.1 kQ/|wT2
4、级偏置电路计算:取几3 =10幅3 =10x0012 = 0.12mA小 小cgl2 = 4VsVcc -12-4取标称值68 kQ故： R -_221 = 66.67kQI 0 12，Rb34b3 = L32Hb3 = 0. 122 x 68 = 0.979mWW选仆 68 kQ J W88R = 21 = _3 =i= 37.04kQ 取标称值 36 kQ4b4 L ，bq2 0-12-0.012 0.108h4 =4m24 =0.1082x36 = 0.42mW-W 选 36 kQ/-W IxD4tKDQ OH-汁r _ Kq2 - Keq2 _ %Q2 - %eq2 _ 4 一 7 _
5、 3.3 _ ? 723kQe2 -7Z - （l+/?）/RO? - 101x0.012 - 1.212 - .凡2分为62（交流负反馈）、&2”，取2 = 56d R/ = 2.7kC4c2 = /EQ22/?c2. =1.2122x0.056 = 0.082mWiw 8%优=&2, = 1.2122 x 2.7 = 3.97mWiw选Re2 56Q/iw 选2 2. 7kQ/-W 88A =匕c-%EQ2-%Q2 = 12-4-4 + 0.7 = 3 92ko取标称值 3.9kQ小21.2%2 = %Q；Rc2 = 1灸 x3.9 = 5.62mW(3-10)2班(62+七)= (3-1
6、0)x2兀 x 50x(3.9+5.1)x103(3-10)x3.54 = 10.62四35.4(iF取。3 = 10)iF选 G 10|iF/16VCel：27ix50x4.3xl03=(3 10) x 7.4 = 222(iF74|iF取 Cei=47|jF 选 Cd 47|JF/16V271x50x2.7x1()3”媪L)x取 Ce2=47|jF 选 Ce2 47|jF/l 6V8 .指标核算Ri=18.7k Q 10k Q 满足设计要求%二兄2=6. Ik Q9 1x6=&凡- = 3.652kQL1七9.1 + 6.1鼠=4& = _100x* = TlV1与 34.483 9x5
7、1R=二- = 2.21kQl 9 l 3.9 + 51R2 21Av? = -lOOx = -26.85V2Rn8.23v = 4 A；2 = T1 x (-26.85) = 295 250 满足设计指标要求。核算/h、/l：A：Q = (Rs + RJG = (0.05 + 18.7)x103x10x10-6=1 87.5ms卬=心个广+冗)/&0所今*+凡)氏00342x43 xlO3x47xIO = 14.89ms0.342 + 4.3% =(% + &)Q =(9. 1 + 6. 1) x 1 ()3 x 10 x 10 = 152msX心/我常+小+凡)心Q=0.146义2.7 X03 *47x 10-60.146 + 2.7=0.139 x 103x 47 x 10-6 = 6.51ms- + + )xlO3 14.89 152 6.51/ 1kl 1/12k2”115 4乙 271x1.15 187.5=32.2Hz 50kHz满足设计要求