# RC Bandpass Filter Help

• romanus_romeo

#### romanus_romeo

Cutoff Freq. = 1/2piRC.
Theoretical bandwidth = 5000 - 1000 (APP) = 4000

But when I do it practically Or simulate as in the pic
Bandwidth = 10000(Around).

I asked the teachers in my college they say I did the practicals wrong. Those teachers gave signatures to everyone in the class even when they got the answers as I had.

#### Attachments

• 34j2n3p.jpg
35.3 KB · Views: 461
31 Views and not a single comment or answer ! Ahh Never mind I got the ans.

well I asked my teacher at college. She is very cool! She told me the following.

f = 1/2piRC for LowPass and HiPass Filter. When the cutoff frequency of lowpass and hipass sections in Bandpass is close to each other, then the input that the other section receives is not full (ie. Vo of one section should be app= Vin) which causes the Maximum output voltage to be very less. Also following formulas can be easily understood for one interested.

Vo R1 * XC2
-- = ------------------------------------------
Vin sqrt(R1^2 + Xc1^2) * sqrt(R2^2 + Xc2^2)

When the cutoff of high pass is reached then R1 = Xc1 and R2 = Xc2. Also there are related searches on the google.

One should get more that 0.707 Vi as output, inorder get the proper results.