A slew rate-controlled output driver having a constant transition time over the variations of process, voltage and temperature

A slew rate-controlled output driver using capacitive feedback is described in this paper. To make a constant transition time in the output driver, a constant current source is used with capacitive feedback between output and the gate of output driver. The capacitor feedback path gives a current path which connects the gate of the output driver with the output during the output driver's transition period to sustain a constant slew rate. The proposed output driver was designed using a 0.13 μm CMOS process. According to our evaluation, the transition time variation of the proposed output driver due to PVT variations is improved by 92% compared to the conventional output driver, and the variation due to the output load variation of 10∼100 pF in typical process, voltage and temperature condition is also improved by as much as 467 %.