An 11 μ w, two-electrode transimpedance biosignal amplifier with active current feedback stabilization.

Area of Science:

• Biomedical Engineering
• Electronics Engineering

Background:

• Two-electrode biosignal recording systems often suffer from baseline drift and amplifier saturation.
• Existing systems may have high power consumption, limiting portability and application scope.

Purpose of the Study:

• To demonstrate a novel two-electrode biosignal amplifier circuit with reduced power consumption and improved performance.
• To address common-mode voltage issues inherent in two-electrode biosignal acquisition.

Main Methods:

• Utilized a composite transimpedance amplifier input stage with active current feedback.
• Employed micropower, low gain-bandwidth product operational amplifiers with off-the-shelf integrated circuits.
• Characterized amplifier bandwidth (0.05-200 Hz), midband voltage gain (48 dB), and output noise (1.2 mVpp).

Main Results:

• Achieved the lowest reported power consumption (11 μW) for a commercial integrated circuit implementation.
• Active current feedback effectively controlled common-mode voltage, minimizing drift and saturation.
• Demonstrated a high signal-to-noise ratio (approaching 50 dB) for typical electrocardiogram (ECG) signals.
• The proposed circuit's performance closely matched standard three-electrode ECG recordings, with a residual power of 0.54%.

Conclusions:

• The novel two-electrode biosignal amplifier offers a low-power, high-performance solution for biosignal acquisition.
• The circuit's active current feedback mechanism enhances stability and reduces artifacts in two-electrode systems.
• This technology is suitable for electrocardiogram (ECG) and potentially other biosignals like electroencephalogram (EEG).