\small K_U = \cfrac { s^2 \, \cfrac {1} { 1 + R_0 \left( \cfrac {1} {R_1} + \cfrac {1} {R_2} \right) } } { \cfrac {1} {C_1 \, C_2 \left[ \, R_1 \, R_2 + R_0 \left( R_1 + R_2 \right) \, \right]} + s \left( \cfrac {R_2 + R_0} {C_1 \, \left[ \, R_1 \, R_2 + R_0 \left( R_1 + R_2 \right) \, \right]} + \cfrac {R_1 + R_2} {C_2 \, \left[ \, R_1 \, R_2 + R_0 \left( R_1 + R_2 \right) \, \right]} \right) + s^2 }