The Design Of RF Circuit And Antenna For WCDMA Base Station

With the fast development of personal communication and mobile communication in the whole world, there are increasing requirements for the service quality of mobile communication. As one of the three standards of the third generation,WCDMA (Wideband Code Division Multiple Access) had been widely used because of its excel-lent communication quality and high spectral efficiency. In the WCDMA receiver, RF front end circuit is very important. Its performance directly affects on the sensitivity and signal processing of WCDMA recriver. So it is valuable to research and design the WCDMA RF circuit.The antenna and low-nosie amplifier (LNA) are the critical components in the RF receiver. Based on abroad reference of domestic and overseas literature, the microstrip antenna's broadband techniques and LNA's basic design principles are deeply re-searched in this paper. After studied many papers, a type of broadband microstrip an-tenna for WCDMA base station, which is loaded with both L-probe feed and double E-slots, is proposed. With the help of electromagnetic simulation software HFSS, ef-fects on the antenna' performance of different size of the proposed patch have been stu-died. On this basis,optimized design of the broadband microstrip antenna for WCDMA base station has been presented, and the antenna is fabricated and tested. The results of the simulation and test both show that the-10dB return loss bandwidth of the antenna is 520MHz, the broadside gain at 2GHz is 7.88dBi. They meet the demands of the WCDMA base station.Besides, according to the performance of LNA which WCDMA base station re-quests, a two-stage amplifier with high linearity has been designed by using the simula-tion software ADS(Advanced Design System) in this paper. The circuit principle dia-gram is given, and the layout is made. The results show that the gain of the LNA is more than 30dB and the nosie figure is less than 1dB at 1.92GHz～1.98GHz. They meet the demands of the WCDMA system and this LNA has some good applied value.