| In this thesis, an active double balanced CMOS mixer module, which can be used in spectrum detection receivers for cognitive radio was designed. The range of the input frequency of the mixer is 470-870MHz.Firstly, the background about the mixer module was introduced, and then the cognitive radio technology, which can solve today's low using rate of spectrum resources was also illustrated. The research significance, concept description, and present research situation were explained. Then the structure of various receiver structures, the advantages and disadvantages of each receiver were analyzed. The receiver structure of the spectrum detection receiver system was fixed on the basis of the above work.Secondly, the performance and architecture of the mixer were explored. The working principle and realization of the mixer were introduced. Comparation was performed among the mixers with various structures. We gived detailed theoretical analysis of each improved approach to make sure the theoretical probability in the design. The core of the mixer was a Gilbert mixer unit. The topology structure of the mixer was improved by using the echniques of multi-tanh transconductance bias, the tcurrent-injection technology in switch stage and the LC load.With the help of Spectre RF of Cadence, the simulating was performed for the mixer circuit by using the standard TSMC 0.18μm CMOS technology process parameters. The simulation results revealed that the voltage conversion gain could achieve 26.13-26.185 dB, the noise figure was 14.498-14.60 dB, the third-order intermodulation was about 7.03-10.36 dBm, the maximum feed-through between every two ports was is less than-55 dB, the total power dissipation was about 21.6 mW when the supply was 1.8 V. Then, the layout of the mixer circuit is designed by using the Virtuoso of Cadence, and the DRC,ERC,LVS verification were successfully operated. The approved mixer has good performance, which meet the requirements of the receiver system. |
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