An increasing number of applications demands for integrated amplifiers able to drive highly variable loads. Emerging non volatile memory technologies have a storage element which presents highly variable resistance and needs well controlled current pulses to be programmed to the required state. In this paper, we propose a unity gain buffer amplifier which is able to drive resistances variable by up to three orders of magnitude and provide them with an adequate amount of current (up to 0.45 mA for a 10 kΩ load), as is required for programming operations of new-generation non volatile memories. The buffer, which is implemented with high voltage devices, has an input/output common mode from 0.4 V to 4.5 V with a supply voltage of 6 V and is able to reproduce fast pulses (down to 50 ns) with minimum rise and fall times of 15 ns.