Study On The Electronic Amplification System Applied In The Measurement Of Laser Radar Cross Section

The content of this paper is how to design a low noise preamplifier and a biquadactive band filter for the measurement of Laser Radar Cross Section(LRCS). Most ofthe low noise amplifiers available are used in radio frequency application, with a lowinput impedance, which is not suitable for the measurement of LRCS. In this thesis,low noise preamplifier is required to have high input impedance, low noise and highmagnification at1KHz. The active filter employs the biquad active band filter whichhas low sensitivity, a center frequency of1KHz, gain of1000and quality factor of100.This thesis analyses the basic principles of the Lower Noise Amplifier(LNA),with its emphasis on the design of parameters and low-noising methods of the LNA.The following part discusses the noise matching between LNA and the photoelectricdetector and solves the LNA’s magnification and its noise coefficient.The basic theory of biquad active filter is also analyzed in this thesis, with thefocus on the design method of the biquad active band filter, which is followed by thediscussion of the sensitivity of the biquad active circuit due to the variation of RCcomponent’s magnitude and integrated operational amplifier’s gain. Finally, theparameters of the biquad active band filter which meets the requirements are obtained.According to the parameter obtained, the circuits of LNA and biquad active bandfilter are simulated respectively. Then experimental data are obtained by testing both ofthe actual circuits, which satisfies the expected result.