UC Irvine

This thesis presents the design and implementation of a glitch-less serializer and a MedRadio-band oscillator, required for neural recording and wireless communication in brain-computer interfaces. The state-of-the-art multi-channel brain signal acquisition relies on analog serialization which suffers from a number of non-idealities such as crosstalk and glitches. To minimize the latter effect, a non-overlapping clock generator logic is employed, which uses a gray-code scheme in the binary counter to avoid race conditions. This approach ensures that bit toggling during the channel sequencing does not cause unintended switching which would have introduced glitches in the serializer. A 4-channel brain signal acquisition prototype is fabricated in a 180nm CMOS process, exhibiting negligible crosstalk and no glitches. For the wireless link, most implantable systems further necessitate an inductorless transceiver design to account for the magnetic resonance imaging compatibility. An ultra-low power MedRadio-band (401-406 MHz) oscillator is demonstrated, which employs a 7-stage current-starved ring oscillator to meet this requirement. Fabricated in a 28nm CMOS process, the digitally controlled oscillator utilizes a coarse- and fine-tuning mechanism to compensate for process, voltage and temperature variations. The oscillator dissipates 114.8 uW at 1V supply and achieves a wide frequency tuning range (~96 MHz) with <60 nS of settling time.