Maximizing Bandpass Filter Bandwidth: Practical vs Theoretical Approaches

AI Thread Summary
The discussion focuses on the discrepancies between theoretical and practical bandwidth calculations for bandpass filters, highlighting a theoretical bandwidth of 4000 Hz versus a practical measurement of around 10000 Hz. The user initially faced confusion over their practical results, which were dismissed by teachers who suggested errors in execution. However, further clarification from a supportive teacher explained that when the cutoff frequencies of lowpass and hipass sections are close, the output voltage is reduced, affecting overall performance. The conversation also includes relevant formulas for calculating output voltage in relation to input voltage and component values. Understanding these principles is crucial for achieving optimal results in bandpass filter design.
romanus_romeo
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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.

Please help. The date for the journal submission are near.
 

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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.
 

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