# Homework Help: Low pass filter operation

1. Mar 8, 2012

### fran1942

1. The problem statement, all variables and given/known data

We have a waveform with peak to peak amplitude 2V and a frequency of 600Hz. If this signal is to pass through a low-pass filter with a passband of 3.5kHz, explain why some distortion may occur to the waveform when shown on an oscilloscope.

3. The attempt at a solution

I thought there would be no distortion because the wave frequency is well below the passband of 3.5kHz.
Can someone please give me some ideas as to why some distortion may occur. Or at least point me in the right direction.
Thanks kindly for any help.

2. Mar 8, 2012

### Staff: Mentor

What parameters are used to express sinusoid?

3. Mar 8, 2012

### fran1942

amplitude, angular frequency and phase ?

Sorry, I am pretty dense !
I still dont see how some distortion would occur in the case I stated.

4. Mar 8, 2012

### Staff: Mentor

Can you write the transfer function for a low pass filter with a suitable cutoff frequency?
For a 600Hz input, what's the output amplitude and phase?

5. Mar 9, 2012

### Staff: Mentor

Are you meant to interpret this to be a sinewave?
You might need to expand your notion of "distortion" to be able to answer this question.
What forms of "distortion" did you consider here?

6. Mar 10, 2012

### rude man

Hint: what is the shape of your voltage? Does it look like a sine wave, triangular, spiky, square .... ?