Implementation of a high-frequency digital lock-in amplifier

A high-frequency digital lock-in amplifier that uses non-uniform sampling is proposed and validated experimentally. By using a random sampling strategy, it is possible to process periodic signals of frequencies several times greater than the Nyquist frequency, which is given by the sampling theorem. The implemented instrument, based on a digital signal processor and its associated hardware, is described in this paper. Experimental results show the advantages of the proposed lock-in