System Analysis of a SMOX Sensor Impedance Spectroscopy Interface Based on Chopper Stabilized Amplifier with Correlated Multiple Sampling

This paper presents a system-level analysis of an electrical impedance spectroscopy readout architecture for semiconducting metal-oxide sensors. The proposed architecture employs a chopper stabilized amplifier coupled with a correlated multiple sampling method to effectively eliminate the offset and attenuate the low-frequency noise introduced by the amplifier. Furthermore, the system exploits the mixer-free digital quadrature demodulation technique to extract the in-phase and quadrature components of the signal obtained from the sensor. The trade-offs of the proposed architecture for impedance spectroscopy applications are analyzed. The results of the simulations are discussed to emphasize the effectiveness of the proposed solution showing an increase in SNR of up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{+ 1 2. 6 5 ~ d B}$</tex> with respect to the correlated double sampling technique.