An LSK demodulator for sub-scalp EEG recording

There is a growing demand of chronic, wireless neu-rosenor interface with on-the-fly processing capabilities. Such neu-rosensor interface is designed with low power, low noise operation, thus meeting the urgent clinical needs of providing long-term, neurological health monitoring for patients who suffer from conditions such as epilepsy, Alzheimer´s disease, and sleep apnea. In this paper, we present an LSK data demodulator to decode sub-scalp EEG data for seizure detection and treatment. The demodulator consists of a multi-phase envelope detector that extracts the envelope of the power carrier and a 10-bit SAR ADC to digitalize the envelope waveform, which can work under a variety of modulation indexes and different coding/decoding protocols. The circuits are fabricated in a 0.18 μm CMOS process and can support a flexible power carrier frequency and data rate. When simulated with a 20 MHz power carrier, the achievable data rate is 2.5 Mbps at a total current consumption of 3.6 mA.