For modern display systems, thorough testing of the TFT array is a critical element in yield management. However, for system-on-panel displays which integrate drivers, timing units, and controllers on the same substrate (usually glass) as the TFT array, access to the array data and scan lines is complicated. To reduce the tester complexity, we propose a low area overhead and offset compensated charge sensing capable source driver design which facilitates built-in TFT array charge sensing. To reduce the number of test access ports, a serial voltage readout scheme is proposed. Simulation results using LTPS technology are shown to validate the proposed technique.