The 128-Channel Fully Differential Digital Integrated Neural Recording and Stimulation Interface

We present a fully differential 128-channel integrated neural interface. It consists of an array of 8 X 16 low-power low-noise signal-recording and generation circuits for electrical neural activity monitoring and stimulation, respectively. The recording channel has two stages of signal amplification and conditioning with and a fully differential 8-b column-parallel successive approximation (SAR) analog-to-digital converter (ADC). The total measured power consumption of each recording channel, including the SAR ADC, is 15.5 ??W. The measured input-referred noise is 6.08 ?? Vrms over a 5-kHz bandwidth, resulting in a noise efficiency factor of 5.6. The stimulation channel performs monophasic or biphasic voltage-mode stimulation, with a maximum stimulation current of 5 mA and a quiescent power dissipation of 51.5 ??W. The design is implemented in 0.35-??m complementary metal-oxide semiconductor technology with the channel pitch of 200 ??m for a total die size of 3.4 mm ?? 2.5 mm and a total power consumption of 9.33 mW. The neural interface was validated in in vitro recording of a low-Mg²⁺/high-K⁺ epileptic seizure model in an intact hippocampus of a mouse.