Applied To The Sdr, Down-conversion Mixer And Design

With the development of wireless communication technology, now there are many different communication protocols in the world. To meet the requirement of different communication protocols, reduce the cost of system and enhance the flexibility of hardware realization, the concept of Software Defined Radio (SDR) is put forward. SDR technology can enable a mobile terminal to be used in many different systems without any resistance. Just because of its high flexibility and strong adaptability, this technology is getting more and more attention.Down mixer is one of the most important modules in SDR receiver system. The main function of a down mixer is to convert the signal from RF frequency to IF frequency. This work focuses on the design of down mixer for TD and GSM application, including circuit theory analysis, parameters calculation, chip implement and measurement.Firstly, the basic theory and spec of mixer are presented. Then the SDR receiver system architecture is presented, from which the down mixer specification is derived.Secondly, Gilbert mixer and the passive mixer are presented. And the performance of the mixer is analyzed in detail.Thirdly, a wideband CMOS passive mixer integrated in Software Defined Radio (SDR) receivers is presented including the circuit design and parameters calculation. And the simulation results are presented.Finally, the chip design and measurement results are presented. The chip achieves good performance in the required frequency band, and can satisfy the application.