- 2072 Chaitra · 2+3 marks
Scaling a ladder to 1000 rad/s and 75 Ω load
Short answer
With kf=1000 rad/s and km=75 Ω, scaled elements: C1=1.3/(75×1000)=17.33 μF, L2=(75×1.5)/1000=112.5 mH, C3=1.2/(75×1000)=16 μF, L4=(75×0.5)/1000=37.5 mH, RL=75 Ω. Passband edge 1000 rad/s.
What is the significance of normalization and de-normalization in filter design? The following is a low pass filter with ωp = 1 rad/sec. Modify the circuit so that it becomes a low pass filter with a pass band of 1000 rad/sec and a load resistance of 75 Ω. [Figure: source V1, shunt 1.3 F capacitor, series 1.5 H inductor, shunt 1.2 F capacitor, series 0.5 H inductor, 1 Ω load (output V2)]
Significance of normalization and de-normalization
Filter tables and prototypes are given for = 1 rad/s and 1 Ω. Normalization lets one table serve every filter and keeps calculations simple; de-normalization (scaling) converts the prototype to the actual frequency and impedance level with practical element values, without changing the response shape:
Numerical
Given prototype ( = 1 rad/s): shunt = 1.3 F, series = 1.5 H, shunt = 1.2 F, series = 0.5 H, load = 1 Ω.
Required: = 1000 rad/s and = 75 Ω.
112.5 mH 37.5 mH
o---+---UUUU----+----UUUU----+
V1 | | |
17.33uF 16 uF 75R V2
| | |
o---+-----------+------------+
Answer: = 17.33 μF, = 112.5 mH, = 16 μF, = 37.5 mH, = 75 Ω; passband edge 1000 rad/s. (If the source has a 1 Ω resistance it also becomes 75 Ω.)
✓ Answer checked by Claude Sonnet 5.5
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