A CMOS Read-Out IC for Cyanobacteria Detection With 40 nApp Sensitivity and 45-dB Dynamic Range

Abstract

This paper presents a low-power high-sensitivity CMOS read-out integrated circuit (ROIC) realized in a 0.13 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ {\mu }\text{m}$ </tex-math></inline-formula> CMOS technology for cyanobacteria detection and monitoring with the current sensing capability of nano-ampere levels. The proposed CMOS ROIC consists of a current-conveyor transimpedance amplifier (CC-TIA) and a 9 bit successive approximation register (SAR) analog-to-digital converter (ADC). Electrically measured results of the proposed ROIC demonstrate 98.6 dB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> transimpedance gain, 1.19 pA/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\surd $ </tex-math></inline-formula> Hz noise current spectral density, and 1.8 mA current consumption from a single 1.2 V supply. The ROIC can precisely recover the digital output codes corresponding to the input current levels of 40 nA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> ~ 7.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$ </tex-math></inline-formula> A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> (i.e., 45 dB dynamic range). Optical experiments utilizing a 405 nm wavelength laser source and a low-cost PIN-photodiode confirm the fluorescence intensity with respect to the quantity of cyanobacteria, demonstrating that the normalized voltage (QD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">655</sub> /QD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">565</sub> ) is a linear function of the mcyD gene copy numbers. The CMOS ROIC chip occupies the area of 1.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 2.0 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .