This work shows an ultra-miniaturised and ultra-low-power CMOS current driver for biphasic intracortical microstimulation. The CMOS driver is composed of a leakage-based voltage-to-current converter and an H-bridge circuit providing biphasic charge-balanced current stimulation. The circuit has been simulated, fabricated and tested. The current driver consumes 1.87 mu W with a supply voltage of 1.8 V, and it occupies a silicon area of 15X12.4 mu m(2) . The driver works in linearity in the current range between 23-92 mu A.