Enhanced ICMR amplifier for high CMRR biopotential recordings

Area of Science:

• Biomedical Engineering
• Integrated Circuit Design
• Analog Signal Processing

Background:

• Biopotential preamplifiers are crucial for amplifying weak biological signals.
• Existing designs often face trade-offs between high common-mode rejection ratio (CMRR), low noise, and high input common-mode range (ICMR).
• Low Noise Efficiency Factor (NEF) is desirable for power-efficient biopotential acquisition.

Purpose of the Study:

• To present an integrated biopotential preamplifier architecture meeting stringent performance requirements.
• To enhance common-mode rejection ratio (CMRR) and input common-mode range (ICMR) simultaneously.
• To achieve low noise and high current efficiency (low Noise Efficiency Factor or NEF).

Main Methods:

• Fabrication of a biopotential preamplifier using a 0.5 μm CMOS process.
• Design of an integrated architecture optimizing for CMRR, noise, ICMR, and NEF.
• Characterization and measurement of the fabricated preamplifier's performance.

Main Results:

• The fabricated preamplifier achieved a gain of 47 dB and a bandwidth of 1 Hz to 7.7 kHz.
• Equivalent input noise was measured at 1.8 μV_rms.
• Demonstrated high performance with CMRR of 100.5 dB, ICMR of 1.7 V, and NEF of 3.2.

Conclusions:

• The proposed integrated biopotential preamplifier architecture meets state-of-the-art performance.
• The design offers enhanced ICMR and CMRR, suitable for demanding biopotential applications.
• The low NEF indicates good current efficiency for portable or implantable systems.