Variable-gain, low-noise amplification for sampling front ends.

Area of Science:

• Biomedical Engineering
• Analog Integrated Circuit Design
• Low-Noise Amplifiers

Background:

• Accurate recording of small biopotentials (e.g., electrocardiogram, electroneurogram) requires specialized low-noise amplifiers.
• Existing amplifiers may lack configurable gain or sufficient noise performance for diverse biomedical applications.

Purpose of the Study:

• To present a novel low-noise front-end amplifier with configurable gain.
• To target the precise recording of small biological signals such as ECG and ENG.
• To demonstrate the amplifier's performance using simulations and measurements.

Main Methods:

• Designed a continuous-time input stage using lateral bipolar transistors in CMOS technology.
• Incorporated a switched-capacitor integrating stage for signal processing.
• Achieved adjustable voltage gain by modifying the phase delay between system clocks.

Main Results:

• Fabricated chip in 0.35-μm CMOS technology.
• Achieved a nominal gain of 630 V/V with over 50-dB tuning range.
• Reported input-referred noise below 16 nVrms/√Hz and common-mode rejection > 97 dB.
• Demonstrated low power consumption of 280 μW with ±1.5-V supply.

Conclusions:

• The developed amplifier offers a compelling solution for high-fidelity biopotential signal acquisition.
• Its configurable gain, low noise, and high CMRR make it suitable for various biomedical monitoring systems.
• The design showcases the effectiveness of CMOS technology for advanced analog front-end circuits.