I never had to deal with a full sheet, but what I used to repair a 4x2 hole from a bunch of ducting I relocated after removing a wall, was use my skill saw set to the appropiate thickness of the existing sub floor (even a bit 32nd shy to avoid hitting the joists). Cut it into a bunch of smaller pieces rather than taking out several larger peices especially if its glued (the extra cutting time is more than made up in the removal time). On two sides the hole open on half a joist. Once you have the hole, have cleaned all the joists and have a peice cut to fit, I installed 8"x17" (~space between joists) pieces of subfloor under the existing subfloor between the joists and glued and screwed them with 4" sticking out. Then I glued and screwed the patch.
This worked well, but might be overkill. Been 6 months now and no squeaks or play yet.