Effective input noise temperature

Voltage

Engineering

Flicker noise

Operational amplifier

Noise figure

Common-mode rejection ratio

Amplifier

Computer science

Power supply rejection ratio

Transistor

Current mirror

Image (mathematics)

Electronic engineering

Artificial intelligence

Noise (video)

CMOS

Electrical engineering

Total harmonic distortion

IEEE Transactions on Biomedical Circuits and Systems

This paper presents a low-power and low-noise capacitive-feedback amplifier with a current-reused OTA for ECG recordings. To improve the noise-power efficiency, the proposed OTA employs a current-reused architecture, which adopts an inverter-based differential input stage for low noise, and a class-AB output stage for large output range and high gm/I efficiency. The driving branch of the class-AB output stage is merged into the input stage to realize current reuse and reduce power consumption further. Fabricated in a 0.35-μm CMOS process, the amplifier consumes 160 nA from a 2-V supply, while achieving an input-referred noise of 2.05 μVrms, corresponding to a noise efficiency factor (NEF) of 2.26. The measured common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) exceed 65 dB and 70 dB, respectively. The total harmonic distortion (THD) is less than 1% with a 15-mVpp input at 20 Hz and the active area is 0.3 mm × 0.6 mm.

A Low-Noise, Low-Power Amplifier With Current-Reused OTA for ECG Recordings