100. Which of the following statements are correct for active filters?
- A. Multiple-feedback are preferred for Q ≤ 10.
- B. For Q > 10, state-variable filter is used.
- C. The upper and lower cut-off frequencies have arithmetic symmetry about centre frequency fc for smaller Q values.
- D. As Q is increased, the filter becomes less selective and both upper and lower cut-off frequencies approximate geometric symmetry.
Choose the correct answer from the options given below:
Correct Answer: 1
Solution:
- Statement A: Correct. Multiple-feedback (MFB) circuits are simple but get unstable if the "Q" (sharpness) is too high. They are best for Q ≤ 10.
- Statement B: Correct. State-variable filters use more Op-Amps to stay stable at high Q values (Q > 10).
- Statement C: Incorrect. Arithmetic symmetry is an approximation used for High Q, not low Q.
- Statement D: Incorrect. Higher Q means MORE selectivity, not less.