A Charge Balanced Neural Stimulator with 3.3 V to 49 V Supply Compliance and Arbitrary Programmable Current Pulse Shapes

A power-efficient six channel prototype of a neural stimulator, with arbitrary programmable current pulse shapes, and a high voltage compliance of up to 49 V is presented. Rectangular, sinusoidal and exponential shapes are possible, supporting e.g. selective stimulation via anodal and HF block. It features high flexibility in current amplitudes from 2 µA to 10 mA with 9-bit resolution per biphasic current DAC, current settling time constant of 0.8 µs, and low voltage headroom. Each channel is equipped with passive charge balancing by a high voltage switch with adequate on-resistance of 2 kΩ. Two channels are additionally equipped with active charge balancing by a PI-controlled offset compensation. The smallest achievable overall static power consumption is 20.8 µW per channel and 41 µW if active charge balancing (CB) is enabled.