Abstract
Parkinson’s disease (PD) is a common neurodegenerative disorder. The motor symptoms such as tremor and bradykinesia result from the degeneration of dopaminergic neurons in the substantia nigra. Deep brain stimulation (DBS) is a new therapy for Parkinson’s disease. By implanting electrodes to particular regions of the brain and giving electrical impulses with specific frequency, DBS can suppress the abnormal electrical impulses and induce neuronal activity. The brain machine interface (BMI) consisting of both recording unit and stimulator are well developed. BMI can record and detect the abnormal signal in brain of the patient, and then, give the corresponded stimulation. Without wires penetrating animal bodies, the wireless implanted device can prevent patient from infection, while the operating voltage should be lower to reduce power consumption. However, the stimulator has to provide high voltage for effective stimulation, so a voltage multiplier is indispensable. This work proposes a voltage-tunable stimulator combined with CMOS-compatible high-voltage transistors, i.e. drain-extended MOS (DEMOS). With a supply voltage of 1V, the output voltage can vary from 3V to 8V, according to 5-bit digital control signal. This design has low power consumption because the charge pump circuit adjusts output voltage automatically. Therefore, the proposed stimulator is suitable for applications in implanted brain machine interface. Applying DEMOS allows it to be integrated with the BMI system in one chip. Two test chips are implemented in a TSMC 0.18μm CMOS process to verify the proposed stimulator design.