Engineering Board Exam Reviewer · Passive Filters · hard
The band-stop (notch) filter shown has R=220, , L=25 mH, and C=400 nF. At what frequency is the output voltage (ideally) zero?
- 10 kHz
- 0.796 kHz
- 3.18 kHz
- 1.59 kHz
Answer
D. 1.59 kHz
Solution
At f0= 12πsqrt(LC) the series L-C branch has XL=XC, so its impedance is 0 and it shorts the output to ground. f0= 12π (0.025)(0.4×10-6)=1.59 kHz.
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