先求 (R4|Ry(1+ R2、,(R3R (+R R3+(R4∥R)R1∥R2R4+(R3∥R)R∥R2 R (R/R) R (1+-) R4、(R3∥F R × R3R3+(R1fR)R∥R2R4R4+(R3∥R)R∥R2 (1+ R、R )+nv2(1+n R R2 R1∥R2R4R2∥R2 (R∥R2)+R、R1,A v3+vis) R R R∥R2RR3R R R R RR R 式中Rp=R3/R4R,Rn=R1/R2Rf R先求 ) // (1 ( // ') ( // ') ) // (1 ( // ') ( // ') 1 2 f 4 3 3 i4 1 2 f 3 4 4 i3 op R R R R R R R R v R R R R R R R R v v + + + + + = ) // (1 ( // ') ( // ') ) // (1 ( // ') ( // ') 1 2 f 4 3 3 i 4 4 4 1 2 f 3 4 4 i 3 3 3 op R R R R R R R R v R R R R R R R R R R v R R v + + + +  + =  ) // ) (1 // (1 1 2 f i 4 4 p 1 2 f i 3 3 p R R R v R R R R R v R R = + + + ]( ) // ( // ) [ i 4 4 p i 3 3 p f f 1 2 1 2 f v R R v R R R R R R R R R  + + = ( ) 4 i 4 3 i 3 n p f R v R v R R R = + op v 式中Rp=R3//R4//R , Rn=R1//R2//Rf