EXCLUSIVE: Jim Carrey To Be A Granddad!

Jim Carrey's rocker daughter Jane Carrey is expecting her first baby and her dad is thrilled, RadarOnline.com has learned exclusively. "I am very excited," Jim, 47, said.  "Jane is going to be a great mom."

Jane, 21, fronts her own rock group, the Jane Carrey Band.  The papa-to-be is Jane's long-time boyfriend Alex Santana, who goes by the stage name "Nitro" with his rock band, Blood Money.

"Jane is ecstatic," a source told RadarOnline.com.  "She and Alex are now engaged and are thrilled at becoming parents."

Jane's mother is Jim's first wife, Melissa Womer.  Jim has been dating Jenny McCarthy for several years.