4.6 Post-Reading and Exercises

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10. Determine the components of a passive high-pass filter using the transfer function

determined in the previous point.

11. What are the advantages and disadvantages of a Cauer filter?

12. What are the properties of Chebyshev functions?

13. What property do elliptic functions have?

14. What important property does a polynomial from a Bessel function have in filter

synthesis?

Interference Suppression and Analogue Filtering

1.

What advantages do active filters have over passive filters and what disadvantage?

2.

Calculate an active Butterworth-high-pass filter of 4th order with cut-off frequency

160 Hz into LTspice. Extend the high pass to a band pass with upper cut-off fre-

quency 1.6 kHz. Check the magnitude and phase frequency response.

3.

What is meant by group delay?

4.

How does a frequency dependence of the group delay affect the transmission of

signals?

5.

What is the difference in principle between a selective filter, such as a power filter,

and a Bessel filter?

6.

What is the purpose of a frequency transformation?

7.

With which frequency transformation can a 50 Hz mains hum filter be realised

from a low-pass filter?

8.

Why is a Bessel filter often used when measuring an ECG?

9.

Please determine the poles and zeros and the transfer function of a normalised

Butterworth-low-pass filter of 2nd order and, using a suitable frequency trans-

formation, determine the transfer function of a Butterworth-high-pass filter of 2nd

order which has a cut-off frequency of 0.2 Hz with an attenuation of 3 dB.

10. Determine the components of a passive high-pass filter with the transfer function

determined in the previous point.

11. What are the advantages and disadvantages of a Cauer filter?

12. What are the properties of the Chebyshev functions?

13. What is the property of elliptic functions?

14. Which important property does a polynomial from a Bessel function have in filter

synthesis?