Phase Change Memory (PCM) is a non-volatile memory technology with wide programming window and continuously improving data retention performance. In order to drive the variable load PCM exhibits, the amplifier providing programming pulses to the cell must be able to accurately control pulse parameters. In this paper, we present a unity gain buffer capable of driving resistive loads varying up to three orders of magnitude. The buffer can replicate voltage pulses of amplitude up to 4.5 V with minimum rise and fall times. The study of the circuit behaviour in high-temperature environments demonstrates its accuracy over a temperature range from-50° C up to 200° C, enabling programming of PCM based on innovative materials in applications requiring reliable operation at high temperatures.