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Characteristics of a Filter

A filter has the following characteristics: Attenuation = 3.0 dB from 0 Hz to 2 kHz.
From 2 kHz to 20 kHz attenuation increases from 3 dB to 23 dB in a straight line when plotted on axes of power in decibels (vertical axis) against log frequency ( horizontal axis).

a. Is this a low pass, high pass, band pass or band stop filter?

b. What is the attenuation per decade between 2 kHz and 20 kHz?

c. What is the attenuation at 4 kHz?

d. Is this an ideal filter or does it behave like a real filter?

Solution Preview

a. This is a low pass filter because the attenuation is at its minimum at DC and lower frequency (i.e. 0 Hz to 2kHz).

b. The attenuation per decade is 20dB/decade. From 2 kHz to 20 kHz is one decade, or a factor of 10, in frequency. The difference in attenuation between the 2 kHz and 20 kHz is ...

Solution Summary

The low pass, high pass, band pass and band stop filter is computed. The attenuation per decade between 2 kHz and 2 kHz is determined. The solution details whether this is an ideal filter or real filter.

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