Low-Noise Amplifier Circuit for Embedded Electrophysiological Recording with Adjustable Gain and High-Pass Filtering

This paper describes a fully-integrated, differential, dual-channel, gain-adjustable and bandwidth-adjustable neural preamplifier circuit. This chip has been designed to enable commercial-off-the-shelf (COTS) embedded-networked sensors (ENS) to acquire electrophysiological signals from mobile test subjects, while allowing for the user to remotely adjust amplifier gain and high-pass filtering characteristics for dynamically switching between local field potential and spike acquisition. The preliminary data presented in this paper has been derived from circuit simulations in Spectre, as the chip has been submitted for fabrication in a standard dual-poly dual-metal 1.5-mum process. The 2.2 times 2.2-mm² chip will consume 127 muA of standby current per channel while operating from a single 3-V supply. Gain and high-pass corner frequency are voltage controlled, and can vary between 40 to 90 dB, and 0.1 to 1000 Hz, respectively, while rejecting the large DC offsets that occur at the interface between the tissue and electrode surface. The low-pass cutoff frequency is set to approximately 10 kHz. Simulated input-referred noise is 4.4 muVrms between 0.5 and 5000 Hz.