Answer:
If we square both sides we got:
We divide both sides by and we got:
Now we can apply log on both sides and we got:
And solving for n we got:
And replacing we got:
And since n needs to be an integer the correct answer would be n=2 for the filter order.
Explanation:
For this case we can use the formula for the Butterworth filter gain given by:
[tec] G = \frac{1}{\sqrt{1 +(\frac{f}{f_c})^{2n}}}[/tex]
Where:
G represent the transfer function and we want that G =0.1 since the desired signal is less than 10% of it's value
represent the corner frequency
represent the original frequency
n represent the filter order and that's the variable that we need to find
If we square both sides we got:
We divide both sides by and we got:
Now we can apply log on both sides and we got:
And solving for n we got:
And replacing we got:
And since n needs to be an integer the correct answer would be n=2 for the filter order.