Hybrid architecture of a DAC for Neurostimulation

Electrical neurostimulation has been effective for treating and reducing symptoms of neurological diseases, for alleviating some types of chronic pain and for restoring sensory or neuromuscular deficits. Because of the energy and size limitation on fully implantable devices, it is important to keep devices small and at low power. It was already demonstrated that non-rectangular waveforms provide a more energy-efficient neural stimulation. In this article, it is shown how a hybrid architecture of current steering DAC is suitable to this application, because of its specifications: the ability to convert several waveforms directly from digital to analog current signals, low power consumption, small chip area requirement, the capability of sharing common stages and also for its simplicity. An ASIC has been developed composed of four stimulator channels, capable of driving several current waveforms. The design is implemented in 130 nm CMOS technology.