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How do u choose the quality factor of a second order notch filter whose transfer function is given by ((s^2+w^2) / (s^2+(w/Q) s+w^2)? ...where w= angular frequency and Q= quality factor?

Question asked by kirankinhal on Apr 14, 2015
Latest reply on Apr 14, 2015 by KJBob

For a fixed value of w, quality factor can be expressed as Q=wL/R considering an inductive resistive circuit. So it can be clearly seen that as Q increases L/R ratio will increase, which is nothing but the Time constant (T) of the system. Generally it can be approximated that a system takes 5-6 time constants to reach the steady state. Hence as T( which can be treated as a function of Q in this case)  increases the circuit will take longer time to reach steady state. But a lower Q would mean a higher bandwidth, and lower precision. How to deal with this trade off and choose proper value of Q in the design?

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