Filtros Analogos (Ingles) Cvut

Khaldenn Idriss
Téllez Rodríguez Eduardo Antonio
Pascual Merino Elena Victoria

SIGNAL FILTERING

In this Laboratory exercise an analog filter was given to us. There were to possibletypes: High-pass and Low-pass and our job is find which one is ours.
To find out which one is we have to analyze how the components of the filter are joint. There are the two differentpossibilities:

A: LOW-PASS


B: HIGH-PASS

In our case the two capacitors are connect to the same joint so we have the variant B: High-pass filter.
A high-pass filter allowsfrequencies higher than the cut-off frequency to pass and removes any steady direct current (DC) component or slow fluctuations from the signal. Such filters are often used to stabilize thebaseline of a signal.

From the back of the board you can find the values Ra, Rb, Ca and Cb. For the high-pass filter Ca=Cb, so it is not need to differentiate and we will call Ca=Cb=C.
Ourvalues are: - Ra = 11 kΩ
- Rb = 16 kΩ
- C = 6800 pF


To measurethe amplitude and phase frequency dependence (ϕ) of our filter we use:
• Digital Storage Oscilloscope OS-3060- GoldStar
• 2 MHz Sweep Function Generator- Escort EGC-3230

and we obtainthe following values:

A
[V] Frequency
[Hz] L(ω)=20*log|A|
[V] T1
[ms] T2
[ms] ϕ = (T2/T1)*360
[º]
1 1 325 0.0 0.47 0.33 -107.234
1.68 2 000 4.50619 0.31 0.24 -81.290
2.2 3 0006.84845 0.30 0.25 -60
2.3 5 000 7.23456 0.40 0.36 -36
2.37 10 000 7.49497 0.40 0.38 -18
2.39 20 000 7.56796 0.39 0.38 -9.231


From these values we have to make a plot of the dependence,in logarithmic coordinates.





We can conclude that the shift and frecuency of this high-pass filter are not proportional. And in our case this is a Butterworth filter.