.2 Ghz Wireless Communication Receiver Front-end Development,

There are 3 main standards in 3G, which are European WCDMA, American CDMA2000 and Chinese TD-SCDMA. The first two standards are utilizing frequency division duplex mode (FDD), while TD-SCDMA is utilizing time division duplex mode (TDD). With the rapidly development of wireless communication, the number of user is increasing, and the resources of communication frequency band is more and more tenser. International Telecommunications Union divides all the frequency band of 3G nearby 2GHz, and requires better frequency utilization percent and higher transmission speed, which gives the design of RF front-end circuits new challenges.The Design of TDD RF front-end circuits in receiver of 2GHz are researched in this paper. The basic theory and the main technical targets in wireless communication RF receiver are summarized. According to 3GPP deliberation,we get the system targets.And the design method of RF front-end circuits are introduced, which including the analyzing the system targets, the selecting of system plan, the assignment of link gain, and the simulation of the whole system. Utilizing simulation software, several key circuits are simulated and validated, which are LNA, protect circuits of LNA and Frequency Synthesizer. Finally, the realization of the receiver and test results of the system are proposed. The test results show that the system meets the requirements of the baseband circuits in wireless receiver. The system has already successfully applied in accurate positioning system of 3G.