Millimeter-wave Broadband Harmonic Mixer

In the Millimeter-wave system, the sub-harmonic mixer with excellent performance not only plays a key role in system, but also reduces the cost of signal source and increase the density of integrated system. More and more attention has been paid on the application of the wide-band sub-harmonic mixer with the improvement of the frequency and the bandwidth nowadays. This dissertation makes a research of the wide-band sub-harmonic mixer and designs the sub-harmonic mixer module for the U-band and V-band respectively.The major task is manufacturing two wide-band receiver front-end both in U-band and V-band for the user's requirement. This paper mainly embodies the research part of the sub-harmonic mixer. An excellent mixing performance has to be realized at full frequency band. The conversion loss is required below the 17dB and 20dB respectively, and the isolations are nearly higher than 25dB between every port.According to the requirement and the practical condition, the LO signal input frequency is designed as 1/4 part of the RF frequency, and the input power is 5dBm. Then it is multiplied two times and amplified for power. This paper adopts a pair of anti-parallel diodes (DMK2308) to realize sub-harmonic mixing, and adopts the Monolithic Microwave Integrated Circuits (MMIC) to realize the frequency's multiplication and the power's amplification. The finline circuit realizes the wide-band sub-harmonic mixer circuit.This dissertation introduces the sub-harmonic mixer firstly. It analyses and illustrates the characteristic and technical specification of sub-harmonic mixer. Secondly, it presents and designs the realization method of wide-band sub-harmonic mixer in order to suggest several design plans of feasibility and possibility. Thirdly, it has made some research and experiment both on the characteristic of finline circuit and the different structures of finline. It designs the unilateral finline, the bilateral finline and single ridge finline sub-harmonic mixers according to the different structures of finline. Finally, in the light of finline structure's features, it also designs and analyses on the transition structure, match circuit and signal return circuit. In this paper, a new kind of microstrip-to-finline transition model is developed in order to achieve the aim of integrated application both the microstrip circuit and finline circuit. It can make the system easy to be miniaturized and integrated. In response to different structure of the finline, we design the microstrip-to-unilateral finline, the bilateral finline and single ridge finline transitions respectively. It theoretically analyses and discusses on the feature of transition model. At the same time, an experimental sample is manufactured for test.This paper adopts ultimately the as the user's product. The testing result indicates that the bilateral finline sub-harmonic mixer has a good performance of the wide-band mixing. All test results can meet the demand of the user's project such as the conversion loss, the isolation and the stability etc. In the meanwhile, the unilateral finline and single ridge finline sub-harmonic mixers are also manufactured for study. A good characteristic of wide-band mixer can be realized in both these two kinds of circuit structures and also get some different application features. Finally, we discuss and analyze on the factors which influences the module performance according to the testing result. We suggest some measures and plans for improvement and perfect.As the important component of receiver system in Millimeter-wave, wide-band sub-harmonic mixer has an obvious role. Its prospect and application are widespread applied in civilian or military region. This assignment design of wide-band sub-harmonic mixer may be a practical reference for study and development in future.