915-MHz FSK/OOK Wireless Neural Recording SoC With 64 Mixed-Signal FIR Filters Karim Abdelhalim, Student Member , IEEE, Larysa Kokarovtseva, Jose Luis Perez V elazquez

Abstract

A system-on-chip (SoC) neural recording interface with 64 channels, 64 16-tap programmable mixed-signal FIR filters and a fully integrated 915 MHz OOK/FSK PLL-based wireless transmitter is present ed. Each recording channel has a fully differential ampli fier with 54 dB gain and utilizes a tunable low-distortion subthreshold MOS-resistor to reject DC offsets with an input-referred noise of 6.5 µV and a CMRR of 75 dB. Each channel contains a modi fied 8-bit SAR ADC with an ENOB of 7.8-bits and can provide analog-digital multiplication by modifying the the sampling phase of the ADC. It is used in con- junction with 12-bit digital adders and registers to implement 64 programmable transposed FIR filters. The 915 MHz FSK/OOK transmitter offers data rates up to 1.5 Mbps and a maximum output power of 0 dBm. The 4×3 mm² chip fabricated in a 0.13 µm CMOS process dissipates 5.03 mW from a 1.2 V supply. Experi- mental measurements characterize the electrical performance of the wireless SoC. In vivo measurement results from freely moving rats are also presented.