Research On Key Components Of Ku-band Receiver Front-end

As the receiver develops towards higher frequency bands,the performance requirements of the receiver are getting higher and higher,and the improvement of the receiver performance mainly depends on the key components of the front end of the receiver.This article takes a Ku-band satellite communication receiver as the relevant background.Study the key components of the front end of the Ku-band receiver:Ku-band low-noise amplifier,Ku-band band-pass filter and intermediate frequency filter.The low noise amplifier as the receiver front stage,its noise figure and gain have the most important influence on the receiver sensitivity.This paper designs a Ku-band low-noise amplifier with high gain and low noise based on the QPA2735 chip.The design process includes chip selection,stability analysis,matching circuit design,and joint simulation of schematic and layout,and it is processed and tested..The measured gain is 18.6dB±0.2dB,the reflection coefficient of the input and output terminals are less than-10dB,the noise coefficient is 1.94dB,and the P_1dB compression point is17.17dBm.As one of the key components of the receiver front-end,the Ku-band bandpass filter is designed to improve the performance of the receiver.In this paper,four different bandpass filters are designed.The first one is a waveguide cavity filter designed based on the computer-aided debugging method of equivalent circuit model parameter extraction.Its simulation bandwidth is 300MHz,the in-band reflection coefficient is less than-20dB,and the signal suppression of the upper and lower stop bands is better than 61.7dB.The second is to achieve the miniaturization of the filter.The asymmetric loading of metal ridges in the resonant cavity produces a capacitive effect to shorten the filter length,and the asymmetric metal ridge waveguide filter is developed by a multiple step method that can effectively shorten the development cycle.The measured bandwidth is 300MHz,the in-band reflection coefficient is less than-11.57dB,the insertion loss is 2.26dB,and the out-of-band rejection of the upper and lower stop bands is better than 75dB.The third is to improve the insertion loss of the second filter.The second filter structure is improved by using a half-processing scheme along the E-plane and a symmetrically loaded metal ridge.Based on this,a symmetric metal ridge waveguide filter is designed and tested.The bandwidth is 300MHz and the insertion loss is 0.9dB.The fourth is to realize the planarization and integration of the filter,using SIW technology and multiple step method to develop SIW filter.In fact,the measured bandwidth is 280MHz,the in-band reflection coefficient is less than-15.5dB,and the insertion loss is about 9.9dB.The out-of-band suppression of the stop band is better than64.2dB.As a key component of the receiver,the IF-filter can effectively filter out-of-band signals of the IF output signal.In this paper,a 12-order IF-filter based on a planar folded multi-curved C-shaped resonant structure is studied.The measured bandwidth is320MHz and the in-band reflection The coefficient is less than-14.3dB,the insertion loss is 3.56dB,and the signal suppression beyond the center frequency1.4GHz±250MHz is better than 64.8dB.In summary,the three key components studied in this paper meet the requirements of the index and can be applied to Ku-band satellite receiver systems.