Re: phase shifter
seemagoyal44, electronics_kumar,
An RC circuit (single pole low-pass) will indeed shift the phase of a sine wave. However, a single pole filter is not capable of shifting 90 degrees, unless the frequency is infinity. A two pole low pass filter will do the job. However, it will also attenuate the signal. The single pole all-pass filter has the advantage of being able to shift the frequency by 90 degrees with no attenuation. The phase shift of this circuit is 2 X the phase shift provided by the passive filter consisting of R and C in bar's schematic.
Regards,
Kral
Added after 4 minutes:
The single pole all-pass filter can shift the phase by any value < 180 degrees, depending on the RC time constant. The phase shift will equal 2Atan(w/w0), where:
. w is the radian frequency of interest
. w0 is the cutoff radian frequency = 1/RC