The USA U23 international underwent a surgery for appendicitis which was discovered during a team trip to the States last month and he has not been back in the UK since.
However, Rams boss Nigel Clough has confirmed that Texas-born Doyle will soon be back at Pride Park and admits he is looking forward to seeing how he is progressing.
"Conor flew back on Wednesday and it'll be lovely to see him again," Clough told the club's official website.
"He's been doing some rehabilitation work back in the States but his return will allow us to assess him properly for the first time since the operation, and we'll take it from there.
"We've been in touch with him over the internet in the last few weeks so the medical team have been able to communicate with him as normal, and they seem to be happy with his progress.
"We'll still be guided by the doctors with regards to when he can rejoin training and eventually return to action for the Under-21s, but hopefully it won't be too long."