Microwave Communication System Transmitter Technology Research

The study of transmitter of microwave communication technology is presented. Because of the intermediate frequency modulation frame, it makes the transmitter more flexible. It operates at 26GHz, which fits for middle and high-capacity microwave communication system. Local oscillator signal is generated by sampling phase locked loop and doubler. Up-converter consists of the single-sideband balanced mixer. Finally, two cascaded monolithic microwave integrated circuit (MMIC) power amplifiers make up of power amplified circuit.For the limitations of the bandwidth and precision of manufacture, rat-race upper-sideband balanced mixer is utilized in order to realize up conversion. To avoid the problem of connection between lead diode and microstrip, flip chip GaAs Schottky diode is used that also could reduce the parasitic parameter. After the analysis of the fundamental principle of the up-converter circuit, simulation the circuit by Serenade 8. 7 is taken. Finally, the results of the simulation satisfied the requirements. Because sampling phase locked loop does not multiple the noise of phase detector and loop amplifier of N, sampling phase locked loop has a lower phase noise compared with the traditional digital multiple phase locked loop. The cascade structure of power amplifier is two-stage amplifiers. The whole amplifier structure is realized by MMIC power amplifier chips, which improve the reliability and density of integration of the transmitter.