A Low-Noise VCII for Biosignal Conditioning

This paper presents the design and analysis of a novel low-noise Second-Generation Voltage Conveyor (VCII) specifically tailored for the conditioning of low-amplitude bioelectrical signals. A key contribution of this work is the comprehensive noise analysis and optimization of the VCII for low-frequency biomedical applications, as, for example, ECG. The focus was specifically put on flicker noise (1/f noise), as it is the dominant noise source in the typical biomedical frequency range of 1-100Hz. Designed using a standard AMS 350 nm CMOS technology and powered at 1.5 V, the circuit confirms the intrinsic properties of the VCII. Simulations show the correct low-power behavior presenting an output voltage noise density of 1.2μV/VHz at 100 Hz at terminal Z, an input current noise density of 102pA/√Hz at 100 Hz at terminal Y and an input voltage noise density of 1.2μV/√Hz at 100 Hz at terminal X.