Investigations On The Multi-mode And Multi-band Receiver Module Based On Digital IF Technology

WCDMA, CDMA2000 and TD-SCDMA are three international standards for the third generation (3G) mobile communication system. This paper focuses on the research to design a receiver based on digital IF technology, which can be compatible to WCDMA,CDMA2000 and TD-SCDMA systems.As the part of the "863" key project:Wideband Multi-mode and Multi-band RF Technology,this paper accomplished the simulation and hardware designing of the Multi-mode and Multi-band receiver module that covers the channel between the antenna and the baseband.Firstly,some schemes of Software Radio were discussed,and some reasons were came up with to prove the Digital IF scheme realizable and ascendant.The bandpass sampling theory and variable speed digital signal processing were described in detail.Secondly,according to some specifications established by 3GPP and 3GPP2, the structure of the receiver module was designed.The key parameters were assigned among stages of the system. The receiver model was simulated by software ADS and Matlab.Thirdly, some appropriate chips were selected to implement the system. It consists of several cell circuits such as a RF Switch, two Low Noise Amplifiers, two Mixers, an IF SAW Filter, an IF Amplifier with AGC, three PLL Frequency Synthesizers, an analog-digital converter (ADC) and a Digital Down Converter(DDC), etc.Finally, the testing procedures and results of the receiver module were given, along with the analysis of their performances, which can be found satisfying the requirements.