Flight Crew Air Transport Pilot (ATP)
Deviation - Speed All Types; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Returned To Clearance
Procedure; Human Factors; Environment - Non Weather Related
I was PM during a visual approach backed up by the ILS 27L into ORD. Just prior to reaching the FAF the aircraft was completely configured; on speed; localizer and GS. As the Captain began to make the SOP FAF calls; I started to key the radio to check in with Tower. He raised his right hand off of the thrust levers to indicate to me to wait so that we could make the calls then check in with Tower (aviate; navigate then communicate). In that brief moment we caught the wake of the preceding aircraft (not a heavy); the autopilot disengaged while the stick shaker started. I do not believe we were even 10 knots below ref at the time. The Captain canceled the autopilot alarm; added power; and continued the approach. The aircraft was never more than a half a dot off LOC or GS.
CRJ-200 First Officer reported a momentary stick shaker occurred after encountering wake turbulence on approach to ORD.