The Design And Implementation Of The X-band Low Noise Receiver Front-end

A receiver on X-band is an important part of the radar system, with thedevelopment of microwave technology, there are higher requirements on the receiver. Inorder to obtain high linearity, wide dynamic range, high sensitivity, high resolution, andstronger anti-jamming capability, there exists development potential for the X-bandreceiver, the corresponding research is more and more in-depth.This thesis completes the work of studying the X-band low-noise receiverfront-end subsystem, using the super heterodyne architecture, it can receive the RFsignal at frequency of9GHz to10GHz. First, the RF signal passes through the lownoise amplifier, because the subsystem requires a smaller noise index, so the noisefigure of the low noise amplifier must be low enough, then the signal passes the filter tofilter out spurious signal and image frequency signal, the signal is down converted withthe local oscillator signal through the mixer, it can generate the IF signal of1to2GHz.The local oscillator signal source is the dielectric resonator oscillator, the oscillationfrequency is11GHz. The design of this paper consists of two parts, the part of the localoscillator signal includes a dielectric resonator oscillator, a low noise amplifier and twofilters; RF part includes a low noise amplifier, a band-pass filter, a mixer, an IFamplifier, and ultra-wide stop-band low-pass filter.This paper first introduces the receiver theory, including common receiverstructure analysis, analysis of technical indicators; developed the X-band receiverfront-end design based on theoretical analysis and design requirements; indicatorssimulation of the system and validation using simulation software. Then it introducesthe design of every device, the low noise amplifier using two cascaded structure ensuresnoise figure is small enough, and increases the gain; the band-pass filter design selectsof the structure of the parallel coupled to have a more a good frequency selectivity andlow insertion loss; the low-pass filter in order to achieve ultra-wide stop-bandcharacteristics, uses a hairpin impedance line resonator unit composed of two low-passfilter cascade structure to complete the design. Finally, according to the index, the writerchooses a suitable mixer and IF amplifier. The local oscillator part includes the design of a dielectric resonator oscillator anda band-pass filter, it first introduced the basic theory of dielectric resonator oscillatorand phase noise characteristics, using parallel feedback structure through analysis andcomparison, and including the design of the dielectric resonator oscillator and thelow-noise amplifier. The band-pass filter has the structure of the hairpin line and filtersout spurious signals generated by the oscillator. All devices are integrated and theoverall receiver front-end subsystem is produced and tested. The last of the paperincludes the theoretical analysis of the test results and giving the improved method.