For the following circuit i am having trouble finding the following respective cutoff frequencies as i am unsure on if i need to take in to account R3 for the high pass portion. Also for the low pass portion do i need to take into account R1 and R2 or not as i know what Vin1 will be?
R1 and R2 are used as a voltage divider as Vout1 has to be less than a certain voltage due to the use it entering an amp after.
Hence what are the formulas i need to use to calculate the cutoff frequencies for say 15Hz - 50kHz? Can i just do for the highpass fc=1/(2pi*(R1+R2)*C) and for the lowpass portion fc=1/(2*pi*R3*C)? To find Vout1 can i just do Vin1*(R/(R+1/jwc))?
Also so are R1 and R2 in series? Then if they are what is R3 in terms of R1 and R2 (as in parallel OR series configuration)
UPDATED: For this given example when i analyse it like the the first plot it gets the correct cutoff frequencies that i am expecting. The problem is that i dont get how to calculate the resistor values for when the voltage divider is used. As it can be seen when i tried, the cutoff frequencies are not what i want and are far off. Hence what equations do i use to calculate R1,R2 and R3 as i assume for the second plot all resistors matter for each filter. First plot gets 20Hz and 15kHz for the -3db cutoff however the second plot is around 20Hz and 5kHz?
Thus how i calculated the lowpass resistor value is wrong and was wondering what formula is needed for fc for the lowpass.