3、放大电路的动态分析 R b R U=l(R+re=1(r+r 0=-1R BR R R.+ R=R3、放大电路的动态分析 ( ) ( ) i i b be b b be U = I R + r = I R + r    o c Rc U I  = −  b be c i o R r R U U Au + = = −     b be i i i R r I U R = = + Ro = Rc