A Wcdma Communication System Transceiver Front-end Technical Studies

Wireless-Transdusing Network that uses the popular technology of WCDMA may change many kinds of information (such as libration, temperature, presure and so on) into electric signals, and then transmits them wirelessly. Nowadays, it is widely applied in many martial aspects, including battlefield spy, information processing and secret communication. The technology of the Radio Freqency discussed in this dissertation is also widely used in civil affairs such as mobile telephone communication. In the thesis are presented the key techniques of CDMA, such as spread spectrum, demodulation and then the circuit design of WCDMA. According to its function, RFCS (radio freqency circuit system)is divided into three parts:transmitting circuit,receiving circuit and frequency source of digital and analogue frequency synthesis. In order to realize the design of low cost and high efficiency, the direct modulation technique is used in RFCS.But to reach low noise and wide dynamic range, is used in the RF circuit the two-cascade technology:one for low noise amplifiers and the other for two automatic gain controls.In the frequency source,are used the advanced direct digital synthesis (DDS) and Phase-Locked Loop (PLL), the low spurious and high-resolution system. In the end of the thesis, from practical engineering piont of view are disscussed the electro-magnetic compatibility, the mix of the digital-analogue and the debugging about the transmitting and receiving circuits. The main test outputs are given and show the design successful.