How do i set the band filter such that it has a pass band of 100Hz to 300Mhz?
That's much easier in the frequency domain. You simply get
$$V_o(\omega) = V_i(\omega)\cdot \frac{1}{1+j\cdot \omega\cdot R_1 \cdot C_1}\cdot \frac{j\cdot \omega\cdot R_2 \cdot C_2}{1+j\cdot \omega\cdot R_2 \cdot C_2}$$

The first term is the lowpass and the second term is the highpass. To set the frequencies you need 
$$R_1 \cdot C_1 = \frac{1}{2\cdot \pi \cdot 300MHz}$$
and
$$R_2 \cdot C_2 = \frac{1}{2\cdot \pi \cdot 100MHz}$$