Design of digital lock-in amplifier based on ZYNQ-7020
Shengting Fan, Z. A. He, L. H. Xing, N. Chen, Duxing Fan · IET conference proceedings. · 2022
In the case of small displacement of the inductive sensor, the inductance change is converted into a weak signal of voltage output through the AC bridge. At the same time, in order to be embedded, it is necessary to study the digital lock-in amplifier. In this paper, the FPGA part of the zynq-7020 controls the DAC to generate the sinusoidal excitation signal of the inductance through SPI communication. The FPGA also controls the ADC to collect the sensor signal and the sinusoidal excitation signal generated by the DAC as the reference signal. After the digital phase-locked demodulation is realized in some resources of the FPGA, the displacement related signal is transmitted to the ARM part of the zynq-7020 through the AXI4 bus, and transmitted through the UART serial port.