Digital Phase-locked Amplifier Research Based On Fpga

When doing research on the objective world, people usually need to detect veryweak signals in some extreme conditions. With the rapid development of sciencetechnology, weak signals detection are continually developing and widely applying inmany projecting fields. Lock-in amplifiers as the main instruments in weak signaldetection are valued for their advantages. In this paper, according to the workingprinciple of the lock-in amplifier, a novel digital lock-in amplifier based on the FPGAwas designed. This paper includes several aspects as follows:(1) According to correlating demodulation principle and cross-correlation detectiontechnology, the paper puts forward the method of dual-channel correlating demodulator.(2) According to the characteristics of the FPGA, a kind of lock-in amplifier wasdesigned. The system takes an FPGA chip as the core logic control module.(3) Designed and analyzed the band pass filters, the operational amplifier, ADC,and the relevant schematic diagrams are given.(4) Deal with the signals in FPGA with double channel coherent demodulationprocessing and vector calculations. Used of Nios II embedded processor in FPGA todisplay the final result of detection on TFT-LCD. Besides, debugged the hardware andthe software of the system, analyzed the results of debugging. The result shows that thesystem can meet the purpose of the design successfully.