The Circuit Design Of Variable-gain Low-power Multiband Frontend

With the proliferation of wireless standards and frequency bands,the manufacturers of consumer electronics have tried to integrate many features in a single hand-held device.This has given rise to a need for receivers that are compatible with as many standards and frequency bands as possible.Low noise amplifier and mixer is the main power consumption module of wireless receiver,and low power design in recent years is trend in development of integrated circuit design.So it is of great significance to reduce the power consumption of RF front-end in receivers.Besides,the design of low power RF front-end in academia and industry has been a hot research topic nowadays.The background and research status of multiband RF front-end and low-power RF front-end is summarized in the thesis.At the same time,on the basis of the traditional narrow band structure,a tunable RF front-end with multiband narrowband frequency selection structure is optimized,which solves the compromise problem of multiband and low power consumption.The LNA is single-input cascode structure with source inductance degeneration,because single-end structure and current-reused technique reduce the power consumption.Meanwhile the center frequency of the RF frontend can be adjusted by changing the resonant capacitor of LC resonant load,in order to cover the entire working band.The mixer adopts passive structure,which consists of transconductance stage,switch stage and transimpedance stage.The transimpedance stage proposes the g_m-boost common gate amplifier which adds the negative feedback on the common gate amplifier to enhance the intermediate frequency transconductance,so as to realize the virtual ground effect of the intermediate frequency signal.So that the absorption efficiency of the intermediate frequency current is improved and the power consumption is reduced.Moreover,the LNA and the mixer can achieve adjustable gain by changing the equivalent load impedance to accommodate different intensity input signals.The schematic and layout of the proposed variable-gain low-power multiband frontend is designed in SMIC 55nm RFCMOS technology.The post simulation results show that the designed RF frontend in this paper can work in the 1.7GHz~2.5GHz band at 1V power supply voltage,and the noise figure is less than4dB,the conversion gain is adjustable from 3dB to 36dB with the step size of 3dB,and the power consumption is 1.91mW.