(2) d2 d 2 d(单) 20 R id 2 R B(RC∥R2) c2 bI R tr b2 2( B oC2 2 R R c(单) B B ic2 (RC∥R2) Ro+re +(1+ B)2R R K d(单) L CMR(单 c(单) b2 2 RB+2+2(1+/)R R B RR U B ic2 2(RR +rhe) 2RE 2R E2( ) ( // ) B be C L R r R R + =  2 2 2 ( 2 i d od i d od ud U U U U A − 单）= = 2 2 2 ( i c oc i c oc uc U U U U A 单）= = B be E C L R r R R R (1 )2 ( // )   + + + = − ＋ － Uod2 R L ＋ V1 V2 Uid1 Uid2 － － ＋ RC Ib1 Ib2 Ic2 R B R B ( ) ( ) ( ) 单 单 单 uc ud CMR A A K = 2( ) 2(1 ) B b e B b e E R r R r R + + + + =  ＋ － Uoc2 R L ＋ V1 V2 Uic1 Uic2 － － ＋ RC Ib1 Ib2 Ic2 2RE 2RE RB RB (2)