Hello all, this is kind of a side project and could use some help on a passive RC bandpass filter I am constructing. The parameters I need are a center frequency at 3800 Hz and 10% tolerance on upper and lower cutoff so upper is 4180Hz and lower is 3420 Hz. I have used this link (http://aries.ucsd.edu/najmabadi/CLASS/ECE53B-LAB/05-W/LAB/filter.pdf) to solve for my resistors and capacitors and simulated through Multisim, but I am still not getting a correct graph where my cutoffs are at -3dB. I am using the bode plot instrument on Multisim and I keep getting a graph where my center frequency is correct but at the wrong gain.
My calculations thus far:
I am told to make the high pass filter resistor lets say R1 much larger than R2 on the low pass filter. So..
(High pass)
ωc=ω(lower)=2∏*3420=1/(R1C1)
R1 is chosen to be 100kΩ
C1=.4653*10^-9
(Low pass)
ωc=ω(upper)=2∏*4180=1/(R2C2)
R2 is chosen to be 10k
R1>>R2
C2=3.8*10^-9
here is the bode plot
https://www.dropbox.com/s/fqfqtmuz9wy4xk2/BodePlotofRCBandpass.pdf
Here is the center frequency
https://www.dropbox.com/s/v824ccflx9ky2ur/CenterFreqBodePlot.pdf
The gain is around -5 dB, not what I want.
Any other thing I need to add let me know please!
My calculations thus far:
I am told to make the high pass filter resistor lets say R1 much larger than R2 on the low pass filter. So..
(High pass)
ωc=ω(lower)=2∏*3420=1/(R1C1)
R1 is chosen to be 100kΩ
C1=.4653*10^-9
(Low pass)
ωc=ω(upper)=2∏*4180=1/(R2C2)
R2 is chosen to be 10k
R1>>R2
C2=3.8*10^-9
here is the bode plot
https://www.dropbox.com/s/fqfqtmuz9wy4xk2/BodePlotofRCBandpass.pdf
Here is the center frequency
https://www.dropbox.com/s/v824ccflx9ky2ur/CenterFreqBodePlot.pdf
The gain is around -5 dB, not what I want.
Any other thing I need to add let me know please!