| With the development of micro-electronics and computer technology, passivemicrowave component in wireless communication and radar systems is one of the keypassive components. The low temperature co-fired ceramic(LTCC) technology is anexcellent methods for realizing miniature volume, lightweight, high performance andhigh reliability. As one of the most commonly adopted microwave passive components,the function of mircostrip attenuator is to adjust the input signal power level. Notably,its performance is critical to the parameters of the entire RF circuit system.Based on LTCC technology, the design methodology of microstrip attenuators isexamined in a systematic manner in this thesis. Thereby, two types of small attenuatordesigns are presented as well. Feedback network with odd of microstrip is focused usedas the main method of analyzing passive resistive attenuators. The effects of variousstructural parameters such as the insertion loss and return loss on performanceparameters are examined and quantified through the analysis and simulation. In addition,the methods of optimizing the passive attenuator are proposed in order to eliminate thecauses of affecting performance parameters in the T-type and the π-type structuredevices. Attenuators in the forms of chip device are designed by Ansoft HFSS softwarewhose central frequency are all5GHz with the bandwidth equals to10GHz. The amountof attenuation is3dB,6dB,9dB respectively in the primary and the secondary structures,all of these simulation results match our design requirement well. Meanwhile, based onthe characteristics of the PIN diodes, the ADS software is used to simulate and optimizethe active attenuator models. The bridge "T"-type passive attenuator which is added abias circuit can design a narrowband attenuator whose central frequency is1.5GHz withthe bandwidth equals to1GHz. The low attenuation is less than1.1dB and the highattenuation is more than10dB; Taking advantages of the characteristics of the dualdirectional coupler, broadband microstrip attenuator is designed perfectly whose centralfrequency is8GHz with the bandwidth equals to4GHz.The low attenuation is less than1dB and the high attenuation is more than20dB. |
