CB and and his ex-girlfriend, Ammika Harris, are expecting their first child together, and sources in the know tell us … it’s a boy.

The child will be Ammika’s first, and a half brother to Brown’s 5-year-old daughter, Royalty, whom he shares with Nia Guzman.

We’re told Chris and his baby mama — who are no longer together — are getting along well. She’s happy with the way Chris is treating her … financially, medically and emotionally.