The Design Of WCDMA RF Optic Module

As the construction of WCDMA network in the world, the network coverage becomes an inevitable issue for operators. Fiber optic repeater is widely applied in GSM, CDMA and PHS communication systems, which resolves the coverage problem well. Therefore the fiber optic repeater will play an important role in WCDMA system. As the key part of the repeater, the quality of the coverage network is directly affected by the performance of RF optical module. The purpose of this paper is to design a WCDMA RF optical module, which can fulfill the need of WCDMA fiber optic repeater and realize the coverage of WCDMA network.On the base of analysis of the GSM and CDMA RF optical module, this paper expatiates the theory of RF optical link and proposes a solution for WCDMA RF optical module. At first this paper brings forward a voltage control attenuator composed by PIN diode, which has good linearity, wide dynamic range and low cost. Then it discusses the theory for coupled line micostrip BPF and realizes a zig-zag micostrip BPF to attenuate spurious emission. After that this paper introduce a method using only one FSK chip to fulfill the function that was achieved by two chips in the past. This way is costly and develops the integration of this module. At last a cavity is designed to solve the EMC/EMI problem of the module.This paper introduces the design theory for each part and realization of the whole hardware. During this period, ADS and HFSS are applied to optimize the design, which predigests the design greatly. The WCDMA RF optical module has unique dual cavity construction and pluggable data transmission module, which realizes the modularization and flexible update ability of the module. This WCDMA RF optical module has passed the filed test for repeater supplier, all the parameters meet the access standard for WCDMA and achieves good performance.