Research On Three Millimeter Wave Vector Modulator

The vector modulator, as a typical application of direct carrier modulation, has been widely studied recently. After having been researched for 20 years at abroad, the vector modulator is very mature now and it has been applied in many fields such as digital communication system, radar cancellation system and phased array radar. However, the domestic research about vector modulators has began in recent years. Due to the limitation of the processing craft, the products have not been applied widely in high frequencies at domestic. In this thesis, an MMIC I-Q balanced vector modulator for W-band is designed based on the MMIC processing line of company WIN, and then the design of vector modulator modeling is achieved. Because the vector modulator for W-band is barely reported at domestic, the research in this thesis has important value for the future development of this field.First, this thesis introduces the advantages of I-Q balanced vector modulators contrasting with other common vector modulators, and analyzes its operating principle. Then an MMIC I-Q balanced vector modulator for W band is designed based on the MMIC processing line of 0.15μm GaAs PHEMT. The processing of the design is detailed in this thesis, including the choices of quadrature coupler and inphase power combiner, and some attentions in MMIC designing. The layout design of the MMIC balanced bi-phase amplitude modulator and MMIC balanced vector modulator are based on the simulation software ADS and HFSS. In the designing, we find that the dynamic range of the balanced bi-phase amplitude modulator is small. In order to extend the dynamic range of the balanced bi-phase amplitude modulator, we increase the characteristic impedance of the Lange couplers which are used for bi-phase modulator from 50 ohm to 70 ohm, and the monolithic area is smaller. The simulated results show that the attenuation of the balanced bi-phase amplitude modulator is from 9dB to 40 dB, and it realizes bi-phase modulation. The phase error is less than 2°. Both of the input and output return losses are larger than 14 dB in the whole W-band. The dimension of the monolithic is 1.4mm×0.7mm. The smallest insertion loss of the balanced vector modulator is 11 dB, the smallest all-phase insertion loss is 15 dB. The phase can change at the whole 360°. In the whole W-band, both of the input and output return losses are larger than 14 dB. The simulated results reach a good level. The size of the monolithic is 1.9mm×1.3mm.Because the MMIC vector modulator in this thesis is not fabricated, a vector modulator module is designed by hybrid integration with a W-band MMIC balanced bi-phase amplitude modulator. At last, the module is fabricated, assembled and measured. This thesis analyzes the measured results and presents improved scheme.