A ramp buffer circuit includes an input device having an input coupled to receive a ramp signal. A bias current source is coupled to an output of the input device. The input device and the bias current source are coupled between a power line and ground. An assist current source is coupled between the output of the input device and ground. The assist current source is configured to conduct an assist current from the output of the input device to ground only during a ramp event generated in the ramp signal.