List<ElementId> viewIds = new List<ElementId>();
viewIds.Add(viewSheet.Id);
DWGExportOptions options = new DWGExportOptions();
options.Colors = ExportColorMode.IndexColors;
options.ExportOfSolids = SolidGeometry.Polymesh;
options.FileVersion = ACADVersion.R2013;
options.HatchPatternsFileName = @"C:\Program Files\Autodesk\Revit 2016\ACADInterop\acdb.pat";
options.HideScopeBox = true;
options.HideUnreferenceViewTags = true;
options.HideReferencePlane = true;
options.LayerMapping = "AIA";
options.LineScaling = LineScaling.PaperSpace;
options.LinetypesFileName = @"C:\Program Files\Autodesk\Revit 2016\ACADInterop\acdb.lin";
options.MergedViews = false;
options.PropOverrides = PropOverrideMode.ByEntity;
options.TextTreatment = TextTreatment.Exact;
document.Export(filePath, fileName, viewIds, options);