Toward the Optimal Architecture of an ASIC for Neurostimulation

Electrical Neurostimulation has been effective in several medical therapies and also for restoring physiological, sensory and neuromuscular deficits. The rectangular pulse waveform has been used as a standard shape for neural stimulation. However, it has been shown that non-rectangular waveforms provide a more energy-efficient neural stimulation. An ASIC has been developed composed of a stimulator, capable of driving several current waveforms, and an analog channel for biosignal acquisition. The design is implemented in 130 nm / 1.2 V CMOS technology, requiring a silicon area of 0.696 mm. Experimental results show that the stimulator can generate analog signals from a digital input of 8 bits. The output stage can drive up to ±9.8 μA, with a DNL and INL of 0.47 and 1.05 LSB, respectively. Its SFDR is 50.2 dB. And it consumes a maximum of 128.12 μW. The analog input channel presents a power consumption of 140 μW, a gain of 52.2 dB, a bandwidth of 0.5 – 1130 Hz and 10 μVrms of noise.