Design Of W-band MMIC Mixer

InP-based high electron transistors(HEMTs) have the traits such as high cut-off frequency, low noise and high gain performance, which have attracted increasing attention in the application of millimeter wave with high frequency in circuit systems. Monolithic MMIC mixer, as one of the core circuits of the front-end transceiver, functions to complete the transfer of frequency spectrum by converting radio frequency signal(RF) at W band to intermediate frequency(IF) signal, which has direct impact on the performance of communication devices. Until nowadays, it remains a big challenge for us to lower the complexity of circuits and at the same time make a MMIC mixer with excellent performance.Based on the InP HEMTs with100-nm gate length, this study examines the critical properties of a balanced resistive mixer and an image rejection resistive mixer at W band. Firstly, by reviewing the foreign and domestic studies on the MMIC mixer at W band, this thesis presents a detailed introduction to the mechanism, design and modeling of the InP HEMTs, then explains principles for resistive mixer units to successfully mix the frequencies with a focus on HEMT devices, and based on that, designs a single-ended resistive mixer. Simulation results show that when the fixed gate voltage VG =- 0.6 V, input LO = 10 dBm @ 94 GHz,RF=-10 d Bm @ 96 GHz, the conversion loss is 7dB and the isolation degree of LO-RF is only 10 d B.In order to improve the isolation degree of this single-ended resistive mixer, a balanced resistive mixer is designed by adopting two Lange bridges. Simulation results show that when LO = 10 dBm @ 94 GHz,RF=- 10 dBm @ 96 GHz, conversion loss is 8dB but the isolation degree jumps to 32 dB. Furthermore, an image rejection resistive mixer is designed with a Lange bridge and a Wilkinson splitter. Simulation results show that the conversion loss is about 8dB, while the degree of image rejection is more than 20 dB.In order to build a system with other circuits, this study explores the encapsulated module of waveguide-microstrip transition circuits, and argues for the use of a fan-shaped probe to couple the TE10 module in the waveguide with the aim of widening working bands. Simulation results show that at the working frequency 83~106 GHz, return loss is less than 20 dB, insertion loss is less than 0.2dB, and band unflatness is less than 1d B. Then to simulate the mixer module with balanced resistive mixer, results show that conversion loss is less than 12 dB.At last, this study tests the tape-out of balanced resistive mixer. Results show that when LO = 10 d Bm @ 94 GHz, RF =-10 dBm, output of IF in the range of 4 GHz, the conversion loss is less than 12 dB, and the isolation degree of LO-RF is over 20 dB.