Stabilized reference current source for biomedical applications

Neurostimulators are devices used to electrically stimulate the nervous system. They are a promising alternative to existing pharmacological methods of treating neurological disorders. The paper presents the current driver, one of the key blocks for providing electrical stimulation. The basic requirements and characteristics of this device are described. The noise of the reference current source, current mirror has been analyzed and the effect of the differential amplifier noise on the total noise current at the output devices has been considered. Based on the results of the analysis, a method for estimating the required output impedance of the current driver is proposed. The circuit implemented in 180 nm CMOS process. The output impedance of not less than 30 MOhm is obtained at the output current of 140 µA and the voltage compliance of 90.9% of the supply voltage. A comparative analysis of the results with the work of other authors is given.