- 2073 Chaitra · 3+4 marks
Frequency and magnitude scaling to 10⁵ rad/s
Short answer
Set kf=1e5 for ωo=1e5 rad/s. Choose km=1000 for 1 kΩ terminations. Scaled: R1=R2=1 kΩ, L1=L2= (1000×2.024)/1e5 = 20.24 mH, C1=0.994/(1000×1e5)=9.94 nF (≈10 nF). Cutoff at 1e5 rad/s (≈15.9 kHz).
Define normalization and denormalisation. Following circuit is a lowpass filter designed at normalization frequency of ωo = 1 rad/s. Apply frequency and magnitude scaling so that ωo = 10⁵ rad/s and practically realizable elements. [Figure 1: source V1, R1 = 1 Ω, series L1 = 2.024 H, shunt C1 = 0.994 F, series L2 = 2.024 H, load R2 = 1 Ω]
Normalization and denormalization
Normalization is designing the filter for = 1 rad/s and 1 Ω terminations, so that standard tables and simple numbers can be used. Denormalization is converting the normalized values to the actual frequency and impedance level using frequency scaling () and magnitude scaling ():
Numerical
Given: , H, F at = 1 rad/s. Required rad/s.
Frequency scaling factor: .
Magnitude scaling factor: with the capacitor would be F and the resistors 1 Ω, which are not practical. Choose (1 kΩ terminations).
1k 20.24 mH 20.24 mH
o-/\/\--UUUU----+----UUUU----+
V1 | |
9.94 nF 1k V2
| |
o---------------+------------+
Answer: = 1 kΩ, = 20.24 mH, = 9.94 nF (≈ 10 nF standard), with rad/s (≈ 15.9 kHz).
Check: product scales by : , so the response shape is unchanged and only moved to rad/s. Any other (e.g. 10 kΩ) is also correct if it gives practical values.
✓ Answer checked by Claude Sonnet 5.5
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