Chad Johnson's Baby Mama -- Make Him PAY UP

Unemployed NFL star Chad Johnson is a deadbeat dad who belongs in jail if he continues his deadbeat ways -- this according to one of Chad's baby mamas.

Andrea Pearson -- who had a son with Chad back in 2010 -- just filed legal docs in Miami, claiming Chad has failed to pay his child support bill of $5,250 on October 15th ... and has consistently been late paying his previous bills.

Andrea claims she doesn't have the means to support the child as a result -- and wants the court to force Chad to pay up ASAP.

If he still fails to pay, Andrea wants the court to throw Chad in jail until he makes good on his child support agreement.

Chad's lawyer had no comment -- but sources close to Chad tell TMZ, he has always provided for his kid, including buying the mother a home.