求静态工作点:
先用戴维南简化基极偏置电路:
ubo=15x3/(56+3)=0.763v
等效rbo=3//56=2.85k
ibq=(0.763-0.7)v/2.85k=0.022ma
ic=βib=1.76ma
rl=∞,vce=15-icrc=15-1.76x5=6.2v
rl=3k,vce=15-icrc-(vce/rl)rc
=15-1.76x5-(5/3)vce
解出vce=2.33v
av=-βrl`/rbe
rbe=100+26mv/ibq=100+26/0.022=1282ω
rl=∞,av=-80x5/1.282=-312
rl=3k,av=-80x(5//3)/1.282=-117
解毕