Microwave And Millimeter Wave Signal Modulation Level Control Technology Research

In this thesis, a voltage control is studied in detail, who can realize 0.25dB step change within the Ka-band while attenuation variation is kept within the range of 0dB to 100dB。A new scheme is presented. Firstly, an upper converter is introduced to realize 34.475GHz±400MHz signal. Then, because the frequency of IF is relative low, a voltage control scheme consisting of two attenuators is used. One attenuator with 0.25dB step change works in the frequency band of IF signal. The other with 10dB step change works in the frequency band of RF signal. By combining the two attenuators, this voltage control can realize 0.25dB step change while attenuation variation is kept within the range of 0dB to 100dB. In addition, based on the theoretic analysis of digital controlled attenuator, the research on an S-band six-bit digital controlled attenuator and a Ka-band five-bit digital controlled attenuator are done. Finally, the simultaneous control of the two attenuators is studied, and then the scheme is proved feasible.In this thesis a modulator is designed, whose frequency band is X-band, isolation is more than 100dB, and the rise and fall time of modulator are less than 50ns, respectively.In order to meet the requirement of the isolation of modulator, the parallel PIN diodes and clapboard are used in the design of the modulator. The measured results show that its insertion loss is lower than 2.8dB and isolation is more than 100dB within the frequency band of 9GHz—12GHz, the rise and fall time are less than 50ns, respectively ,and physical dimension is 35mm×14mm×9mm wide.