A Compact Sub-μW CMOS ECG Amplifier With 57.5-MΩ Z_in, 2.02 NEF, 8.16 PEF and 83.24-dB CMRR

Area of Science:

• Electronics
• Biomedical Engineering
• Integrated Circuit Design

Background:

• Instrumentation amplifiers are crucial for amplifying weak biological signals like ECG.
• Existing designs often face trade-offs between power consumption, noise, and input impedance.
• Micro-power operation is essential for wearable and implantable medical devices.

Purpose of the Study:

• To present a novel DDA-based fully-differential CMOS instrumentation amplifier.
• To achieve micro-power consumption for ECG monitoring applications.
• To optimize for high input impedance, low noise, and power efficiency.

Main Methods:

• Utilized a current-sharing DDA (Differential Difference Amplifier) architecture with only eight transistors.
• Implemented AC-only amplification using an RC feedback network with MOS pseudo resistors and poly capacitors.
• Achieved DC coupling via gate terminals of p-channel input transistors for high input impedance.

Main Results:

• Fabricated in a 0.35-μm CMOS process, occupying 0.0712 mm².
• Operates at 2V with 336 nA current consumption.
• Measured input impedance of 57.5 MΩ at 150 Hz, 1.54 μVrms input-referred noise (0.1-300 Hz), and 83.24 dB CMRR at 50 Hz.

Conclusions:

• The proposed amplifier offers excellent performance metrics for micro-power ECG monitoring.
• Demonstrated functionality in a real human subject measurement scenario.
• Represents a significant advancement in power-efficient, high-performance analog front-ends for biomedical applications.