Design of Automatic Frequency Tracking Digital Lock-in Amplifier
Zhang Jin-mi · Hedianzixue yu tance jishu · 2014
In the design of photoelectric detection system,lock-in detection system is often used to eliminate the 1 / f noise and other powerful noise.In this paper,the digital lock-in amplifier is designed based on DSP Builder of Alter Company.At the same time,in order to avoid the mismatch between measured signal and reference signal,the automatic frequency tracking module is designed,so as to realize the matching with the reference signal frequency,and ensure the measurement accuracy.After simulation,the compiled file is downloaded to the FPGA device,realizing the hardware design by hardware test.Experimental results show that,the SNR(Signal to Noise Ratio) of the measured signal is less than10 d B,the minimum amplitude detection is 50μV,the frequency-locked error is less than 0.015%,the measurement error of the signal amplitude is less than 0.11%,and the design can effectively realize the need of photoelectric detection.