An implantable CMOS analog signal processor for multiplexed microelectrode recording arrays

A second-generation multichannel probe designed for measuring single-unit activity in neural structures is described. The probe includes CMOS circuitry for amplifying and multiplexing the recorded signals and for electronically positioning the recording sites with respect to the active neurons. The probe offers a typical AC gain of 150 (50 Hz to 10 kHz), a DC gain of 0.3, and an equivalent input noise of 13 mu V rms. Eight active recording sites are selected from among 32 on the probe shank using a static input channel selector. The probe implements channel selection, self-tuning data output, and initialization using a three-lead connection to the outside world. The probe is realized using 12 masks in a high-yield single-sided dissolved wafer process with a 3- mu m feature size for the circuitry and a 3- mu m pitch on the electrode shanks.<>