Electrical Engineering ⇒ Topic : Non-inverting mode

Non-inverting mode

In non-inverting mode, the produced output is a linear combination of inputs without a change of sign. The circuit is shown in Figure (a).

                           figure (a)

The output voltage V_o, in terms of R, R_f and V'_i can be expressed as:

                                          ............. (1)

From Figure (a), V'_i, is the summation of voltages contributed by V₁, V₂, , V_n.

The voltage contributed by V₁ can be obtained by using superposition theorem. The contribution to V'_i, due to V₁ is V'i₁ = V₁Rp₁/(R₁ + Rp₁)], where Rp₁ is the equivalent resistance ofparallel combination of resistances R₂, R₃..... R. If R₁= R₂ = = R_n = R', R_p1 = R'I(n -1).

   ........... (2)

Therefore, the contribution to V'_i due to V1,V2,........,Vn can be written as:

                            .............. (3)

Using Eq. (3), Eq. (1) can be written as:

             ............ (4)

The circuit becomes non-inverting summing amplifier.