An Integrated Analog Lock-In Amplifier for Low-Voltage Low-Frequency Sensor Interface

In this paper we propose a low single supply voltage (2V) analog lock-in amplifier, completely integrable on silicon, designed in a standard CMOS technology, for electronic sensor interfaces used in low-frequency applications. In particular, the proposed architecture is suitable for those sensor interfaces where the signal to be measured has a small amplitude and is buried into noise. In these cases, the lock-in amplifier guarantees the signal recovery from noise (till to 0.1 SNR), provided that the generated small signal, coming from sensor, has a fixed and well-known frequency. Together with the integrated solution, waiting for the chip fabrication, we have built a discrete element board, with commercial components, for preliminary experiments which confirm the validity of the proposed lock-in system, since it is able to detect, for example, very small quantities of carbon monoxide (CO).