The Reseach Of Dual-band Image Rejection Mixer Based On CRLH Transmission Line

The mixer is a key device in microwave communication, measurement, remote control and other systems. In modern communication systems, superheterodyne receiver is increasingly widely used, mirroring input will bring great disturbance to the receiver, so the suppression of image frequency becomes very important. With respect to image rejection mixer, which utilizes filters and repetitious inverter technology, the phase-balanced image rejection mixer has wide bandwidth, small size and other advantages. Because of the frequency offset and phase compensation feature of composite left and right transmission line(CRLH-TL), it has a good prospect in microwave circuits: not only can it achieves dual-band device with any frequency ratio, but also can miniaturize the device. A wireless system, which is utilized dual frequency devices, is able to reduce the number of components used and cost savings. Therefore, the study of phase-balanced dual-band image rejection mixer, which is based on CRLH-TL, has some practical values.Firstly, this paper introduces the theoretical basis of the image rejection mixer and CRLH-TL; analyzes the transmission characteristics of CRLH-TL, elaborates the design theory and design steps of how to use hybrid structure with microstrip line and lumped element to achieve dual-band performance of CRLH-TL, introduces the structure of SRR, CSRR, CSR and its equivalent circuit respectively, analyzes the design theory to achieve dual-band performance of CRLH-TL based on defected ground structure.Secondly, we determine the design scheme of the paper. In this thesis, we use the transmission characteristics of CRLH-TL to design the phase balanced dual-band image rejection mixer, the structure of the circuit consists of the following components: dual-band 3d B quadrature couplers of LO terminal, dual-band 3d B power divider of RF terminal, two dual-band single-balanced mixer, IF filter and IF 3d B quadrature coupler.Thirdly, the thesis elaborates the layout and emulation of various components mentioned above. Generally, the device area produced by dual-band CRLH-TL structure based on microstrip line and lumped element hybrid is larger, an improved method is mentioned in the thesis to devise the dual-band CRLH-TL structure. In order to verify the feasibility of the design method of CRLH-TL based on defected ground structure, the paper also used an improved defected ground structure in the design of dual-band Wilkinson power divider, the examination outcomes show that this construction can indeed achieve the dual-band characteristics of CRLH-TL. In this thesis, we use ADS simulation software to design and simulation the dual-band image rejection mixer. From the simulation results, the design can satisfy the indicator well.Finally, the paper introduces the production, debugging, testing process and measurements of the dual-band image rejection mixer. From the measurement results, we can obtain that the conversion loss, isolation and image rejection of the dual-band image rejection mixer can all meet the design requirements in two radio frequency band 2.4 ~ 2.5GHz and 5.725 ~ 5.825 GHz.