Research On High Linearity Down - Conversion Mixer For SDR

With the development of mobile communications, and the demands come from different economies, as well as the different populations, blossoming of multi-mode mobile terminal has become the present, and even future inevitable trend of the mobile communication technology. With the help of software programming method, the emerged software defined radio (SDR) technology enhances the system’s compatibility for multiple communication standards, reduces system overhead and increases system flexibility. Therefore, SDR technology arouses wide concern from the world, and becomes one research hotspot at this stage. Compared to the traditional wireless communication systems, multi-mode wireless receiver is one of the most critical parts of the SDR technology.Functioning as a significant component of the receiver, downconversion mixer converts RF signal into IF signal. Basing on2G and3G protocol, this paper discusses the principle and implementation of mixer, which used to guide the design of a downconversion mixer. Finally, theory and design were verified by tapout.Firstly, this paper introduces the receiver system and mixer module. Compared to several common structure of the receivers for SDR, and provides a brief analysis. Moreover, the basic principles and mainly specifics of mixer were presented.Secondly, active mixer and passive mixer are discussed according to the mainly specific. Detailed analysis and theoretical derivation are presented for the latter design and optimization of subsequent downconversion mixer.Thirdly, a downconversion mixer for multi-mode receiver which is used for GSM, WCDM and TD-SCDMA protocols was implemented in TSMC65nm1P9M standard CMOS process. The optimization of power consumption, linearity, and NF are mostly concerned, which expounded in the discussion of constituent modules. Meanwhile, simulation results are given.Finally, design theory and method were verified through tapeout. The chip layout design, test scheme, as well as the consideration in testing. The test results show that the performance of the mixer achieves the expected targets, and basically meets the system requirements of the software radio receiver.