Question

The lower cut-off frequency of \(N\) cascaded stages is given by

• A. \(f_L (2^{1/n} -1)^{1/2}\)
• B. \(\frac{f_L}{\sqrt{2^{1/n}-1}}\)
• C. \(nf_L\)
• D. \(\frac{nf_L}{\sqrt{2^{1/n}-1}}\)

Hint:

Cascading amplifiers modifies bandwidth limits.

Answer 1

The Correct Option is B

Concept: For cascaded amplifiers, overall frequency response changes.

Step 1: Individual cutoff Each stage has cutoff \(f_L\).

Step 2: Combined effect Multiple stages shift cutoff frequency.

Step 3: Formula \[ f'_L = \frac{f_L}{\sqrt{2^{1/n} - 1}} \]

Step 4: Interpretation Lower cutoff frequency increases for cascaded stages.

Step 5: Conclusion \[ \boxed{\frac{f_L}{\sqrt{2^{1/n}-1}}} \]

Final Answer: \[ \boxed{(B)} \]