This disclosure describes generation of electrical stimulation pulses for electrical stimulation therapy. The stimulation pulses have a pulse current level and pulse width, and may be generated by a current regulator. The pulse voltage level may be a voltage level delivered by the current regulator while maintaining regulation of the pulse current level. During delivery of a pulse, a supply voltage level may decrease due to discharging of a supply capacitance, and the pulse voltage level may increase due to charging of a load capacitance. The pulse current level may be controlled to decrease during the pulse width such that a sum of the pulse voltage level and a headroom voltage of the current regulator does not exceed the supply voltage level. In some examples, the pulse may include sub-pulses with different sub-pulse current levels, where an earlier sub-pulse has a higher pulse current level than a later sub-pulse.