City boss Gary Johnson told the club's official website: "Phil has been very patient so far and because of our good form he hasn't been able to play.
"This loan gives him the opportunity to get some match action under his belt."
Jennison Myrie-Williams has joined League One side Tranmere on a month's loan.
The Robins have given the 19-year-old winger permission to play in Rovers' FA Cup second-round tie against Bradford.
Myrie-Williams spent three months on loan at Cheltenham earlier this season, for whom he scored once in 13 games.