(5)反相求和运算: u=0 =0,i =0 R R F F 1712-1F 12 0 2 R R 2 R F i2 o R F 0 RF Win 虚地 R R P 若R1=R2=R, R 取Rp=R1/R2/RkF (ui1t Ui2 R13 (5) 反相求和运算： _ +  +  R RF 1 R2 ui2 uo RP ui1 i1 i2 iF 虚地 uo =-( ui1 R1 RF + ui2 R2 RF ) 若R1 =R2 =R, uo = - (ui1 R RF + ui2 ) 取RP= R1 // R2 //RF uo _ +  +  RF R1 RP ui u+ = u− = 0 i i b+ =0 b- =0, i1 + i2= iF ui1 R1 = ui2 R2 + -uo RF