A 3.3-to-11V-Supply-Range 10μW/Ch Arbitrary-Waveform-Capable Neural Stimulator with Output-Adaptive-Self-Bias and Supply-Tracking Schemes in 0.18μm Standard CMOS

Neurostimulation has emerged as the cornerstone that enables closed-loop brain-machine interfaces and targeted treatments for many neurological disorders. Regardless of the application, neurostimulators employ implanted electrodes to deliver charge pulses to tissues within safety limits to engender desired neural responses. However, as electrode-tissue-impedance (ETI) varies widely (Fig. 1 (top)), neurostimulators should operate over a wide supply range to ensure both therapeutic effectiveness and safety [1]. When ETI is large, a higher supply is needed to provide adequate stimulation. However, when ETI is low, a low supply is necessary to minimize tissue damage from excessive electrical field and heat rise [1], [2]. Furthermore, power consumption during standby mode limited to under
$10\mu\text{W/Ch}$
ensures no tissue necrosis. Lastly, a stimulator capable of delivering arbitrary stimulation waveforms is also desirable for maximal efficiency and therapeutic effectiveness.