CMOS Low-Power Lock-In Amplifiers With Signal Rectification in Current Domain

This paper presents the design and experimental characterization of two lock-in amplifier (LIA) prototypes integrated in a 0.18-μm CMOS process with a single supply voltage of 1.8 V. As opposed to previously reported integrated LIAs, synchronous rectification is performed in the current domain, providing key features such as low power (<;420 μW) and reduced area (0.013 mm 2 ), with a dynamic reserve better than 35 dB and less than 5% relative error in the signal recovery. The principle of operation of each prototype is presented and their performance is compared with previous implementations, validating their suitability for low-cost portable applications.