基于AD630锁相放大器的微弱信号处理--论文外文翻译资料.pdf

Advanced Materials Research Vols. 482-484 (2012) pp 975-980 Online available since 2012/Feb/27 at © (2012) Trans Tech Publications, Switzerland doi:10.4028//AMR.482-484.975 AD630 Lock-in Amplifier Circuit for Weak Signal Yanli Liu1, a, Rui Zhang1, b 1 College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, China a b lyl87627@, zhangrui@ Keywords: lock-in amplifying (LIA), weak signal detection, phase sensitive detector, AD630. Abstract. Lock-in amplifying (LIA) is one of important techniques of picking up weak signals buried in the noise, and is the core component of Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. Then we design a small size, dual phase lock-in amplifier (LIA). This paper is based on the phase-sensitive detector AD630, together with the phase-locked loop (PLL) circuit (74HC4046) and the active filter (MAX275) the value of Q and the center frequency of which could be adjusted. The output signals were collected by A/D converter and dedicated high-resolution data acquisition card. The range of frequency is 500Hz-100 kHz, the dynamic range of acquisition signal is greater than 100dB, the signal-to-noise ratio is up to 60dB, and the overall area of circuit is only 14cm × 14.8cm. Experiments show that the design meets the requirements of integration into the system. Introduction Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology is a new kind of gas detection techniques developed in these years [1, 2], provided with high sensitivity, high precision, and so on. Among techniques used in TDLAS, the direct absorption method is used to measure small changes in large signal, so that the weak absorption signal is easily hidden i