Spread-Spectrum Modulated Multi-Channel Biosignal Acquisition Using a Shared Analog CMOS Front-End.

Area of Science:

• Biomedical Engineering
• Integrated Circuit Design
• Signal Processing

Background:

• Designing multi-channel biosignal acquisition systems for ambulatory or invasive medical applications faces challenges in power consumption, area, and wire count.
• High channel counts exacerbate these design constraints, impacting device portability and cost.

Purpose of the Study:

• To propose and validate a spread-spectrum modulated biosignal acquisition system to address power, area, and wire count challenges.
• To develop a design methodology for optimizing recording systems based on SNR, input count, and area requirements.
• To demonstrate a low-power, compact analog front-end for high-channel-count biosignal acquisition.

Main Methods:

• A spread-spectrum modulation technique using a shared amplifier and analog-to-digital converter (ADC) was employed.
• A design method was developed to optimize the recording system for specific application needs (SNR, input count, area).
• Pseudo-random binary-sequence (PRBS) codes with a code-length of 511 were utilized for 16 inputs, and a 4-input analog front-end was implemented in a 0.18 μm CMOS process.

Main Results:

• The system achieved an average Percentage Root-Mean-Square Difference (PRD) of 2.65% for sinus rhythm (SR) and 3.02% for atrial fibrillation (AF) on pre-recorded atrial electrograms.
• The implemented 4-input analog front-end demonstrated a 4:1 input-to-output wire ratio.
• The system achieved low power consumption of 23 μA/input and a small area of 0.067 mm².

Conclusions:

• The proposed spread-spectrum biosignal acquisition system effectively reduces power consumption, area, and outgoing wire count for high-channel applications.
• The design methodology allows for system optimization tailored to specific medical monitoring requirements.
• The implemented CMOS analog front-end validates the feasibility and efficiency of the spread-spectrum approach for advanced biosignal acquisition.