Research And Design Of Key Modules Of Reconfigurable Receiver System

As new applications and services for wireless mobile communications are introduced and the demand for higher data rates increases,the need for new frequency bands and standards arises.The current communication equipment needs to support an increasing number of wireless communication standards and frequency bands.Meanwhile,RF receivers,as an important part of wireless communication systems,also should be compatible with as many communication standards and frequency bands as possible.Considering that,in this paper,the design concerning two key modules of the RF receiver front-end,namely the low noise amplifier and the mixer is focused on.Firstly,the dual-band reconfigurable LNA designed in this study addresses the problem that the use of MOS switching tubes to switch frequency bands will affect the circuit performance and how to achieve dual-band applications.By adopting the alternate conduction method to control the bias voltage of the two input tubes,the influence of MOS switching tubes is eliminated,thus achieving dual-band applications;secondly,it aims to solve the problem that the noise and matching performance indicators will deteriorate when switching between the two bands,two LC resonators in the load network are controlled by switch to optimize the performance between the bands.Finally,to deal with the problem of increased chip area between the LNA and the mixer due to the need of connecting the balun and being not conducive to chip integration,the active balun is used to achieve differential output,thus further reducing the area of the chip layout while increasing the gain of the LNA.The dual-band reconfigurable Mixer designed in this paper addresses the issues of how to reduce power consumption,provide good linearity and achieve multiple bands.Firstly,a folded dual-band reconfigurable Gilbert mixer structure is proposed to reduce the supply voltage and power consumption;secondly,the cross-conductor stage of the mixer adopts a differential cross-coupling structure to improve its linearity;finally,an LC resonant cavity is used as the load of the mixer to prevent leakage of the RF signal,while it is controlled by a switch to achieve switching between the dual bands for the purpose of realizing multi-band applications.Both the dual-band reconfigurable LNA and Mixer were designed and simulated on the Cadence Spectre RF based on the TSMC 0.18μm CMOS process.From the simulation results,it can be seen that at a supply voltage of 1.8V,the gain of the dual-band reconfigurable LNA is 12.4～19dB and 14.1～17dB in the 3.3～4.2GHz and 4.4～5GHz bands respectively;the noise factor is 2.8～3.5dB and 3.1～3.4dB separately,and the input matching factor is-10～-24.8dB and-10～-15.9dB accordingly.Besides,the gain in the 3.3～4.2GHz and 4.4～5GHz bands is 11.3～12.8dB and 13.3～13.8dB correspondingly,while the noise factor is 11.5～12.01dB and 9.8～10.3dB respectively,and the third order crosstuning is 2.805dBm and 4.03dBm.The simulation results all meet the design requirements.