A 3V single supply LIA for portable sensing systems

This work presents a 3 V single supply analog lock-in amplifier designed for processing output sensor signals in highly noisy environments. The proposed amplifier uses square input signals instead of the usual sinusoidal signals, consequently allowing a straight interface with microcontroller-based sensing systems, and can be utilized for both resistive and capacitive sensors since it is based on a dual channel rectifier to remove phase dependence of the sensor signal. Experimental results for signals buried in white noise, flicker noise, interference contamination and common-mode voltage contamination confirm the capability of the proposed solution to effectively recover information from signal to noise ratios down to -24 dB with errors below 6% with an average power consumption of only 5 mW in full operation.