功率放大器加模拟题VIP免费

1/41.有一谐振功率放大器，已知晶体管的gc=2000ms,Vb2=0.5V,Vcc=12V,谐振回路电阻RP=130Ω,集电极效率ηC=74.6%,输出功率P～=500mW,工作于欠压状态,试求：(1),VCM,C,C1,C0,CM(2),为了提高效率ηc，在保证VCC、RP、Po不变的条件下，将通角θC减小到600，计算对于C=600的C1，CM，ηc(3),采用什么样的措施能达到将C变为600的目的?题解:(1)P～==>VCM==11.4VC=g1(C)g1()=VCC=1.568查表C=900∴0()=0.3191()=0.5C1m==87.69mACM==175.38mAC0=ICM0()=55.95mA(2)P～和不变，则C1M和不变(∵P～==2C1M∴CM==224.27mACO=CM0(600)=48.89mA2/4c=1(600)=85.5%(3)改变导通角，应改变偏量和Vbm由gc=∵C1M不变，CM(900)=175.38mACM(600)=224.27mA∴Vbm(900)==87.69mV=∴==0.5V即在Vbm=87.69mV,Vbb=0.5s时，导通角900由Vbm(600)==0.24427V==0.5∴Vbb(600)=112.135mV3/4∴Vbm由87.69mV变为244.27mVVbb由500mV变为112.135mV可保证在输出不变时，C由900变为600答案：(1)①VCM=11.4V②C=900③C1=87.69mA④CM=175.38mA⑤CO=55.75mA(2)若VCC、RP、Po不变，C=600C1=87.69mA;CM=224.27mA;CO=48.89mA(3)Vbm由87.89mV变为224.27mVVbb由500mV变为112.135mV2.已知谐振高频功率放大器的晶体管饱和临界线的斜率gcr=0.9s,Vb2=0.6V,电压电源VCC=18V,Vbb=-0.5V,输入电压振幅Vbm=2.5V,CM=1.8A,临界工作状态试求：(1)电源VCC提供的输入功率Po(2)输出功率P～(3)集电极损耗功率PC(4)集电极效率ηC4/4(5)输出回路的谐振电阻RP答案:Po=7516.8mVP～=5904mWPC=1612.8mWηC=78.5%RP=21.68Ω题解:临界时:CM=gcr(VCC-VCM)可得VCM由=得=63.90查表0(63.90)=0.2321(63.90)=0.410