DG-category and simplicial bar complex

In this paper, we prove that the DG category of DG complex of DG category of a differential graded algebra A is homotopy equivalent to that of comodules over the simplicial bar complex of A. Under the assuption of connectedness of A, we show the homotopy category of A-connection is equivalent to comodules on the homology of bar complex. As an application, we construct coalgebras classifying nilpotent variation of mixed Tate Hodge structures on algebraic varieties.