Discussion in 'Electronic Design' started by Samper, May 8, 2005.

1. ### SamperGuest

I have a RC circuit and a imput x=a*expjF. The output is
y 1/1+2*pi*f*R*C)*a*expjF. Why the phase of the output (that for
definition is atan(im/re)) in this case is:
phase=arctg(F-2*pi*R*C)?

2. ### Andrew HolmeGuest

It isn't. The phase of the output is:

F - arctan(2*pi*R*C)

3. ### MichaelGuest

The output phase should be:

-arctan(2*pi*f*R*C)

With this Im assuming that F in your equation is the same as f, they
are both frequencies. If this is not the case and F is the input
phase, then the output phase is:

F-arctan(2*pi*f*R*C)

Dimensionaly arctan(2*pi*R*C) is not a phase, it needs the extra f
inside the arctan.

4. ### Andrew HolmeGuest

Oops .... that was a typo on my part. I meant: F - arctan(2*pi*f*R*C)
I think F is the input phase because the input was given as a*exp(jF) =
a*(cos(F) + jsin(F))

5. ### John SmithGuest

or angular frequency

6. ### Andrew HolmeGuest

No, I don't think so: there's no time variable (as in omega*t)
r*exp(j*theta) is the r-theta (magnitude / angle) expression of a complex
number.  