The filter shown in Figure P15.36 is a Sallen and Key band-pass filter circuit, where $K$ is the DC gain of the filter. Derive the following expression for the filter's frequency response:
$$
\begin{aligned}
& H(j \omega)= \\
& (j \omega)^2+j \omega\left(\frac{1}{R_1 C_1}+\frac{1}{R_3 C_2}+\frac{1}{R_3 C_1}+\frac{1-K}{R_2 C_1}\right)+\frac{R_1+R_2}{R_1 R_2 R_3 C_1 C_2}
\end{aligned}
$$