Design space exploration during high level synthesis is often conducted through ad-hoc probing of the solution space using some scheduling algorithm. This is not only time consuming but also very dependent on designer's experience. We propose a novel design exploration method that exploits the duality between the time and resource constrained scheduling problems. Our exploration automatically constructs a high quality time/area tradeoff curve in a fast, effective manner. It uses the MAX-MIN ant colony optimization to solve both the time and resource constrained scheduling problems. We switch between the time and resource constrained algorithms to quickly traverse the design space. Compared to using force directed scheduling exhaustively at every time step, our algorithm provides a significant solution quality savings (average 17.3% reduction of resource counts) with similar run time on a comprehensive benchmark suite constructed with classic and reallife samples. Our algorithms s...