Design Of High Linearity Broadband Asymmetric SPDT RF Switch Chip

Recently Radio Frequency industry has been growing by leaps and bounds,which promotes the advance of mobile phone terminal structure,intelligent control system,telecommunications market rapidly.Additionally,people become increasingly dependent on the transceiver system with excellent performance of high integration,efficient transformation in military or civil domains.As the key components of RF front-end circuit,the capability of RF switch will directly affects the function of RF system.In this dissertation,high linearity broadband single pole dual throw(SPDT)switch is studied which is used for the transceiver system with asymmetric topology.First section introduces the current demand and the state of arts of the RF switch.The advantages of pseudomorphic HEMT process are generally demonstrated after discussing the process implemented in microwave switch,which can be used for designing better power amplifier,broadband switch,etc.In addition,it can satisfy the requirement of high integration,low power consumption and available cost.Then the specific work includes switch configuration selection based on FET voltage floating theory and practical application,electromagnetic simulation with proper circuit.In order to improving linearity and power performance without destroying other parameters,this thesis adopts tri-gate FET,multi-stacked FETs and feed-forward capacitor.Briefly,the design is complete with the accurate layout drawing.Finally,the RF switch was fabricated using GaAs 0.5?m pHEMT process with chip area of 3*3mm2.The on-chip testing,with proper dc voltage,shows that,in the frequency range of 10MHz-2.6MHz,for the SPDT switch,the insertion loss(IL)is less than 0.5dB,the isolation(ISO)is more than 25dB,the switching time less than 1?s,the capability of power handling higher than 10W.The measured results demonstrate that the chip with small size can meet the requirements for handsets system.