Today I got confused about Low pass filter transfer function. Let's assume we have a simple low pass RC filter . It is well known that at f=fc we expect -3dB (0.707) drop in Vin.
Everyone knows a LPF transfer function is:
On the other hand we know that :
Which results in :
If we set f=fc we will have:
But I expected 1/√2 =0.707 ! I am sure I am missing something but can not find that because this differs from the formula that I knew: