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Passive Filter Circuits
44 questions By Tony R. Kuphaldt
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Question 22 of 44
What kind of filtering action (high-pass, low-pass, band-pass, band-stop) does this resonant circuit provide?
Reveal answerThis circuit is a band-stop filter.
Notes:As usual, ask your students to explain why the answer is correct, not just repeat the answer that is given!
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Question 23 of 44
Identify each of these filter types, and explain how you were able to positively identify their behaviors:
Reveal answer
Follow-up question: in each of the circuits shown, identify at least one single component failure that has the ability to prevent any signal voltage from reaching the output terminals.
Notes:Some of these filter designs are resonant in nature, while others are not. Resonant circuits, especially when made with high-Q components, approach ideal band-pass (or -block) characteristics. Discuss with your students the different design strategies between resonant and non-resonant band filters.
The high-pass filter containing both inductors and capacitors may at first appear to be some form of resonant (i.e. band-pass or band-stop) filter. It actually will resonate at some frequency(ies), but its overall behavior is still high-pass. If students ask about this, you may best answer their queries by using computer simulation software to plot the behavior of a similar circuit (or by suggesting they do the simulation themselves).
Regarding the follow-up question, it would be a good exercise to discuss which suggested component failures are more likely than others, given the relatively likelihood for capacitors to fail shorted and inductors and resistors to fail open.
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Question 24 of 44
Identify the following filter types, and be prepared to explain your answers:
Reveal answer
Notes:Some of these filter designs are resonant in nature, while others are not. Resonant circuits, especially when made with high-Q components, approach ideal band-pass (or -block) characteristics. Discuss with your students the different design strategies between resonant and non-resonant band filters.
Although resonant band filter designs have nearly ideal (theoretical) characteristics, band filters built with capacitors and resistors only are also popular. Ask your students why this might be. Is there any reason inductors might purposefully be avoided when designing filter circuits?
