Microwave Ultra Broadband Power Level Control Technology Research

The microwave power level control circuit is an important part in the microwavefrequency synthesizer. The performance index of power level control circuit plays adecisive influence on the power performance of microwave frequency synthesizers. Theradar, electronic countermeasure, communication, navigation, aerospace and otherapplication fields have an increasingly high demand for power performance offrequency synthesizers, which requires good power flatness in the operating frequencyrange of the frequency synthesizer and also requires the achievement of the signalpower step output. Therefore, the development of high-performance microwave powerlevel control circuit is increasingly important. The microwave ultra-wideband tunablepower level control circuit is demonstrated and achieved, which works from1GHz to10GHz.First of all, this dissertation introduces the review and the correlation theory ofautomatic level control technology which is the key technology of the microwave powerlevel control circuit. The introduction includes classification, structure, correspondingindicator and main components of the automatic level control circuit, and it alsocontains the function analysis of closed-loop automatic level control.Secondly, the closed-loop automatic level control circuit scheme is obtained basedon the subject index. Then, according to components selected in the design, thehardware design of the closed-loop scheme and the details of implementation are given.Finally, the control of the automatic level control circuit is achieved in FPGA andon computers, respectively with VHDL and VB language. With FPGA, when the circuitworks at5GHz, fast power switching in a large dynamic range is achieved; with VB,power flatness and stepper output are achieved from1GHz to10GHz frequency range.The measured results show that, with FPGA, the output dynamic range of the finalcircuit operating at5GHz is greater than25dB, output power step is0.5dB, and the erroris less than0.3dB. With VB, when the circuit works from1GHz to8GHz frequencyrange, the output dynamic range is greater than20dB, output power step is0.5dB, andthe error is less than1dB; when it works from8GHz to10GHz frequency range, the output dynamic range is greater than15dB, output power step is0.5dB, and the error isless than1dB.