Research And Design On RF Front-end Circuit Of B3G Zero-IF Receiver

Due to the wireless communication have requirements of high data transmissionand high quality service, the research of B3G UWB wireless communication technol-ogy has become hotspot at home and abroad.The RF front-end adopts analog mixerto achieve spectrum move generally for the limitation of AD device speed, precisionand other factors.The Zero-IF receiver has become a competitive structure in the RFreceiver for the advantages of high integration and low power consumption.A new dualcarrier—double orthogonal zero-IF receiver scheme is proposed based on the analysisof features of B3G receiver system and traditional Zero-IF receiver in this paper, inorder to solve the problems of IQ imbalance and self-image caused by phase-shift ofzero-IF receiver.The research details are as follow:Firstly, broadband quadrature phase-shift circuit of the receiver RF front-end hasbeen researched and designed, test shows that: amplitude-frequency characteristic andphase-frequency characteristic of its output signal have good e?ect.Secondly, a 3GHz～5GHz low-noise amplifier which can meet low-complexity ofB3G has been designed, and its input has used common-gate structure to achievebroadband matching, and its output has used source with the device to improve theload capacity;The amplifier's maximum gain is 18dB, and the minimum noise figureis 1.7 dB, and the third-order intermodulation point is -1dBm.In addition, mixer of a3GHz 10GHz zero-IF receiver has been design, using the structure of source injectingcurrent and common-source node connecting inductance to eliminate the DC o?setcomponents of mixer;Within range of the frequency band its gain is 12.5dB, and 1dBcompression point is -12dBm, and the third-order intermodulation point is -3dBm, andinput and output isolations are less than -12dB.Finally, through building simulink software model the performances of dual carrier-pairs of orthogonal zero-IF receiver and the traditional zero-IF receiver and their vectordiagramat and constellation diagramat at di?erent phase error have been compared.Testing by the circuit and simulation results are consistent.Simulation and test results show that:when the phase error exists in the system,the improved dual carrier—double orthogonal zero-IF receiver has a better outputvector than the traditional zero-IF receiver, and solved the problems of DC drift andIQ imbalance in zero-IF receiver.Research results have a certain reference value for themarket applications of zero-IF receiver.