Maximizing Bandpass Filter Bandwidth: Practical vs Theoretical Approaches

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SUMMARY

The discussion focuses on maximizing the bandwidth of bandpass filters, specifically addressing the discrepancy between theoretical and practical bandwidth calculations. The theoretical bandwidth is calculated using the formula Cutoff Frequency = 1/2πRC, yielding a bandwidth of 4000 Hz. However, practical simulations indicate a bandwidth of approximately 10000 Hz. Key insights from a college teacher emphasize the importance of ensuring that the cutoff frequencies of lowpass and highpass sections are appropriately set to achieve maximum output voltage, which should exceed 0.707 times the input voltage (Vi).

PREREQUISITES
  • Understanding of bandpass filter design principles
  • Familiarity with the formula for cutoff frequency: f = 1/2πRC
  • Knowledge of voltage output calculations in filter circuits
  • Experience with practical circuit simulation tools
NEXT STEPS
  • Research practical applications of bandpass filter design
  • Learn about the impact of component tolerances on filter performance
  • Explore advanced circuit simulation tools for filter analysis
  • Study the relationship between cutoff frequencies and output voltage in filter circuits
USEFUL FOR

Electronics students, circuit designers, and engineers involved in filter design and optimization will benefit from this discussion.

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.