Research On Design Technology Of Watt-level CMOS Switch

In the modern information society,the application of wireless communication technology in life is ubiquitous,whether it is civilian WLAN,5G mobile communication,Io T base station,and various microwave applications such as military radio and long-range detection radar,all of those promote radio frequency chips to develop in the direction of high performance,broadband and high-power.As the key control module in the radio frequency front end,the radio frequency switch directly controls the mode of transceiver and the switching between different frequency bands.Therefore,a radio frequency switch with low insertion loss,high isolation,and high-power processing capability is the cornerstone of a high-performance radio frequency transceiver system.Firstly,this article investigates the development history and research status of RF switches,and then introduces the development history of the SOI（silicon-on-insulator）process.Additionally,the article introduces other processes for a horizontal comparison to illustrate the advantages of the SOI process,and analyzes the on and off states of SOI CMOS.The small signal equivalent model below.Secondly,this article explains the working mechanism of CMOS switches and the physical meaning of key parameters,and summarizes four important circuit topologies of RF switches.By explaining the shortcomings of the current stack structure in improving the linearity of the switch,the challenges faced by the current high-power CMOS switch design are drawn.Then,based on the analysis of the power limiting factors of the series-shunt FETs-stacked switch,the working mechanism and limitations of using the negative bias method to improve the power handling capacity of the switch are analyzed,and then a new method that can replace the negative bias voltage is proposed,e.g.independent bias method.Through the analysis of the working mechanism of the independent bias method,the voltage distribution of different nodes,the small signal equivalent model,the circuit simulation comparison results,and the actual chip test analysis,the reliability of the technical method is verified.Finally,through the actual test of the Sub-6GHz watt-level power CMOS single-pole double-throw switch chips,the switch achieves an insertion loss of less than 1 dB at 0.8-5 GHz,the isolation is greater than 30 dB,and the return loss is greater than 10 dB.The input P_1dB of the switch is greater than 30 dBm,the switch test performance is close to the simulation performance,and the watt-level power processing capability is realized,which verifies the correctness of the independent bias technology method and the technical method,which is of great significance for high-power CMOS switches.