Abstract
Biological prosthetic system had developed for a long time. The progress in CMOS technology and increasing demand of health management make implantable system become a main stream. The application of such a system including Parkinson's disease, epilepsy, neuromuscular disorders, stroke, paralysis, artificial silicon retina, silicon cochlea, physiology signal monitor, etc. The neural amplifier amplifies and filters the indistinct signal after it is recorded by electrode array. For deceasing design trade-off between power and noise, a two-stage structure is used in this article. A balanced tunable pseudo-resistor is used to acquire local field potential (LFP) and action potential (AP) separately while rejecting unwanted offset voltage induced by tissue-electrode interface. In recent years, the research about interaction between neurons is more and more popular, the multi-channel neural amplifier is essential in this application. However, low power design is desirable, heat produced from the power-hungry chip can eventually injury the deep-skin cells. Action potential detector is usually a choice to reduce power consumption of processor and transmitter. The proposed AP detector combines dual-threshold technique to adaptive threshold setting circuit and only consumes 12.65uW. The article is fabricated by TSMC 0.18um process. The measurement results show that the system achieved input referred noise 4.96mVrms and noise efficiency factor (NEF)3,69 with mid-band gain of 50.4dB and power consumption of 7uW. The bandwidth is highly tunable in the range of 15Hz-436.9Hz for high-pass corner and 317Hz-11kHz for low-pass corner. The results show that the proposed low-power, low-noise biomedical system is suitable for implantable device applications.