\small u_0 = \dfrac {1 + s \left[ \, C_1 \left( R_1 + R_2 \right) + C_2 \left( R_2 + R_0 \right) \, \right] + s^2 \, C_1 \, C_2 \left[ \, R_0 \left( R_1 + R_2 \right) + R_1 \, R_2 \, \right]} {s^2 \, C_1 \, C_2 \, R_1 \, R_2} \ u_1