Research And Design Of X Band Control Module Circuits

Since the 21st century,broadband phased array technology with high precision,multi-channel and large data capacity has continued to thrive to meet the needs of civil wireless communication system and military radar.The phased array system requires a larege number of T/R modules,which are the most critical modules affecting the performance and cost of the whole phased array system.The digital phase shifter and digital attenuator controls the direction and amplitude of the beam.These two kinds of microwave components play a fundamental and vital role in the whole phased array system.Therefore,it remains a hot topic in the academia and industry.In this thesis,the design method and the development trend of phase shifter and attenuator are discussed based on literature reviews.Also,the difficulties in these designs are analyzed.Based on the requirements of the system,higher technical indicators including wider bandwidth and lower insertion loss are proposed.To meet these requirements,an X-band 6-bit digital phase shifter and a DC-13GHz 6-bit digital attenuator are designed based on 0.5?m GaAs pHEMT process.When designing the X-band 6-bit digital phase shifter,this thesis introduces the equivalent model of the pHEMT transistor and then extracts the parasitic parameters of switches of different sizes.The advantages and disadvantages of common phase shifter topologies are analyzed in detail.Based on these analyses,the topology circuit of each phase-shifting unit and the cascade order are optimized.Finally,5.625°and 22.5°phase-shifting units adopt the embedded LC topology;11.25°and 45°phase-shifting units adopt the bridge T topology;90°and 180°adopt high-pass-low-pass topology.At the same time,in order to simplify the control logic of the chip,the level shift circuit and inverter circuit are also integrated on chip.The final simulation shows that the typical phase error of the 6-bit digital phase shifter is 10°during 8-12GHz and the maximum RMS phase and amplitude error is 6°and 0.9dB.The chip achieves very low insertion loss with a typical value of 6dB,and a maximum value of 7.9dB.Both S₁₁ and S₂₂ are less than-12dB.The chip size is 3.1mm×1.05mm×0.1mm.And it can be easily packaged in 5mm×5mm Quad Flat No-leads(QFN)package.In the research of DC-13GHz 6-bit digital attenuator chip,the size of the switch transistor is optimized following the similar method.Also,the tradeoff between linearity and insertion loss is achieved.Finally,the 6-bit digital attenuator achieves very low insertion loss from DC-13GHz,with a maximum value of 4.147dB.At the same time,the attenuation error is less than(0.3+3%×ATT)dB,and the RMS amplitude error is between 0.15dB-0.45dB with a typical value of 0.25dB.The chip also achieves a good performance of linearity.The P_0.1dB is greater than 25dBm.Meanwhile,the S₁₁ and S₂₂of all states are less than-12dB.The chip size is 1.65mm×1.05mm×0.1mm.