A low-power, time-division-multiplexed vector matrix-multiplier for a vestibular prosthesis.

Area of Science:

• Biomedical Engineering
• Neuroprosthetics
• Analog Circuit Design

Background:

• Vestibular prostheses require precise processing of angular rate sensor data.
• Misalignment and spurious electrical stimulation can impair vestibular prosthesis function.
• Analog vector matrix multipliers (VMMs) offer potential for efficient signal processing in implantable devices.

Purpose of the Study:

• To develop and characterize a custom analog vector matrix multiplier (VMM) for vestibular prostheses.
• To address challenges of sensor misalignment and spurious neural stimulation.
• To evaluate the VMM's performance in terms of speed, power consumption, and precision.

Main Methods:

• Designed and fabricated a custom analog VMM using TSMC 0.35 μm CMOS technology.
• Operated the VMM in the CMOS subthreshold region for low-power consumption.
• Employed time-division-multiplexed multiplication to mitigate device mismatch susceptibility.
• Characterized the VMM for 3-by-3 vector matrix multiplication of angular rate sensor outputs.

Main Results:

• The VMM successfully performed 3-by-3 vector matrix multiplication for signals with magnitude <; ±250 mV and bandwidth <; 1.25 kHz.
• A complete operation cycle required 727 μs.
• The fabricated chip occupied a footprint of 1523 μm × 1548 μm.
• The VMM demonstrated a low power consumption of 5.37 μW.

Conclusions:

• The custom analog VMM is a viable component for enhancing vestibular prosthesis performance.
• The VMM effectively reduces sensor misalignment and compensates for spurious neural stimulation.
• Low-power, subthreshold analog VMMs are suitable for implantable neuroprosthetic applications.