An embodiment of an electrically trimmable electronic device, wherein a resistor of electrically modifiable material is formed by a first generally strip-shaped portion and by a second generally strip-shaped portion, which extend transversely with respect to one another and are in direct electrical contact in a crossing area. The first and second portions have respective ends connected to own contact regions, coupled to a current pulse source and are made of the same material or of the same composition of materials starting from a same resistive layer of the material having electrically modifiable resistivity, for example, a phase-change material, such as a Ge—Sb—Te alloy, or polycrystalline silicon, or a metal material used for thin-film resistors. The trimming is performed by supplying a trimming current to the second portion so as to heat the crossing area and modify the resistivity thereof, without flowing longitudinally in …