Research On Mixers For Millimeter/Sub-Millimeter Wave

Mixer is one of the key components in wireless communication transceiver system.With the innovation of wireless communication technology,spectrum resources are increasingly tense,and the applications of frequency are gradually shifting to high frequency bands.In millimeter/sub-millimeter wave band,the traditional fundamental mixing technology,based on high-frequency local oscillator with complicated fabrication and high cost,is difficult to realize.Therefore,the high-frequency harmonic mixing technology has become the mainstream of research.Based on the principle of APDP(anti-parallel diode pair)even harmonic mixing,two mixers are designed in this thesis.Firstly,one millimeter-wave image-rejection mixer,implemented on InP HEMT substrate,is proposed.Using phase balanced topology,unit circuits of the mix(such as Lange bridge,power divider and low-pass filter)are designed and simulated,respectively.Besides,with the introduction of 1/2 RF wavelength short line and 1/4 LO wavelength open line,good isolation between RF and LO ports is realized.The simulation of schematic diagram and layout is carried out successively.Secondly,another submillimeter-wave second harmonic mixer,based on Schottky diode,is presented.The unit circuits(such as shielding cavity circuit,the transition between RF waveguide and suspended microstrip,low-pass filter,LO-IF duplex)are designed and simulated,respectively.Then,above unit circuits are split into the smaller elements(such as transmission line,waveguide and discontinuous transition),which are fitted into ADS.Global optimization method is used to simulate harmonic balance of the whole circuit,restoring the circuit model.In this work,the cavity is drawn,layout is designed and the processed circuit is tested,respectively.For the millimeter-wave image-rejection mixer,under the condition that IF frequency,RF power and LO power are 1 GHz,-20 d Bm and 15.4 d Bm,respectively,in the RF frequency range of 135-145 GHz,the simulation results show that the conversion loss can be up to 15-16.6 d B and the image rejection ratio are all better than 20 d B.In addition,for the submillimeter wave second harmonic mixer,the test results show that the conversion loss is 13.4-17.7 d B in the RF 306-346 GHz range,under the condition that IF frequency and LO power are 10 GHz and 6 dBm.