Engineering Board Exam Reviewer · Passive Filters · hard
In the loaded low-pass filter shown, R1=1 k , R2=1.5 k (the load), and C=100 nF. Find the cutoff frequency.
- 2.65 kHz
- 1.59 kHz
- 0.637 kHz
- 1.06 kHz
Answer
A. 2.65 kHz
Solution
Seen from the capacitor, the resistances are in parallel (the source is a short): Rth=R1 R2=(1000)(1500)/2500=600, . fc= 12π RthC= 12π(600, )(0.1×10-6)=2.65 kHz.
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