Fast and Offset-Leakage Insensitive Current-Mode Line Driver for Active Matrix Displays and Sensors

Current-programmed active matrix (AM) architectures that are independent of fabrication technology are attractive for display and sensor because of their ability to tolerate mismatches and nonuniformity caused by aging. However, the long settling time due to low current levels and large parasitic capacitance can be a significant limitation. In this paper, we present a fast current-mode line driver based on positive feedback which controls the effect of parasitic capacitance. The driver was fabricated in 0.8-mum 20-V CMOS technology. While the measured settling time of a conventional current source is around 2 ms for a 100-nA input current and 200-pF parasitic capacitance, it is less than 4 mus for the driver presented here. Moreover, an offset-leakage cancellation technique is implemented for the fabricated driver to reduce the effect of leakage and offset currents to few nA.