A Low-Power Lock-in Amplifier Suitable for Implementation on a Programmable System on-Chip

A low-power lock-in amplifier suitable for implementation on a programmable system on-chip (PSoC) is proposed. The LIA-based measurement instrument including an ADC and a CPU for signal processing is realized. The proposed LIA suitable for on-PSoC implementation needs just only two operational amplifiers (OPAs) while the conventional LIA does seven. The contrivance to reduce the number of OPAs is useful regardless of the implementation devices to be also applicable to various CMOS IC processes. The circuit analysis with realistic assumptions derives exact formulas to obtain the unknown signal amplitude and phase from the measured voltages on the LIA. Simulation and experimental results are presented to confirm the validation of the proposed LIA.