A CMOS analog front-end chip for amperometric electrochemical sensors

This paper reports a complimentary metal–oxide–semiconductor (CMOS) analog front-end chip for amperometric electrochemical sensors. The chip includes a digital configuration circuit, which can communicate with an external microcontroller by employing an I²C interface bus, and thus is highly programmable. Digital correlative double samples technique and an incremental sigma–delta analog to digital converter (Σ–Δ ADC) are employed to achieve a new proposed system architecture with double samples. The chip has been fabricated in a standard 0.18-μm CMOS process with high-precision and high-linearity performance occupying an area of 1.3 × 1.9 mm². Sample solutions with various phosphate concentrations have been detected with a step concentration of 0.01 mg/L. (paper)