L And S-band High-frequency Transceiver Front-end Study

Microwave transceiver is an important component in the satellite communication system. The basic function of transmitter is to encode the baseband informantion onto a high frequency sine wave carrier signal that can be radiated more effectively than the direct radiation of the baseband signal, and to amplify the microwave carrier, the purpose of which is to meet demand of long-distance transmission. The receiver converts the high microwave carrier frequency to a low intermediate frequency (IF) by using the low noise amplifier (LNA) and mixer and band pass filter (BPF). So microwave transceiver is the hinge of signal chain in the wireless system. This thesis focuses on the research and design of the L band transmitter and S band receiver front.Firstly, in this thesis, the historical development and future trends of microwave transceiver, from circuit, arts and crafts, to system are introduced. Then, a superheterodyne receiver and an improved direct modulation technology are used to carry out the transceiver of the satellite communication. Secondly, some key technologies in practice, such as sensitivity, low noise factor and phase noise, linearity, microwave direct modulation and linear power amplifier are discussed, and some technologies are used to reach the target. A LNA with a low noise factor is designed to determine the noise characteristic of whole receiver. The low phase noise is reached by using serial-digital phase-locked loop (PLL) frequency synthesizer. In order to eliminate the effect of "pull-push" from a large transmission signal in the microwave direct modulation system, an improvement that the transmission carrier doubles the frequency of local oscillator (LO) is applied to microwave transmitter front. A useful approach to the design and tuning coupled-resonator filter using group delay has been described. And a tapped I/Q coupled-resonator filter with low insertion loss and narrow band has been simulated and tuned. Thirdly, the methods of tuning and measuring transceiver front, as well as its results are figured out.