Eight Millimeters Transceiver Front-end Ltcc Technology Research

In microwave and millimeter-wave systems, transceiver front-end is a significant assembly for the whole system performance. Miniaturization, high-speed, high reliability, is the development direction of the front-end system. Low-Temperature Co-fired Ceramic (LTCC) technology is one type of Co-fired ceramic Multi-Chip Module (MCM), which is a high-integration and multilayer-printed packaging technology. Its three-dimension (3D) structure can improve performances and volume of microwave and millimeter-wave circuits and systems, which is an effective way to realize System miniaturization. In this paper, a 8mm miniaturized transceiver front-end is designed based on LTCC technology.Firstly, this paper based on the gap coupling and patch antenna radiation theory, Ka-band LTCC waveguide to microstrip transition with low loss, high integration and high reliability is designed using slot-coupled structure. Secondly, based on lumped parameter model of the interconnection between LTCC layers and the principle of capacitance compensation, we broad the width of the microstrip's end, while introduce an air cavity to reduce the parasitic parameters of the transition section. On the basis of these, two interconnection structures is designed with a good performance in the whole Ka-band. Then, in accordance with the principle of LTCC filter design, two types of narrow-band millimeter-wave band-pass filter and a millimeter wave band-stop filter is designed with the advantages of the small volume occupied and easy to realize in LTCC technology, which resolve the issue of out-band spurious suppression. Finally, according the main technique index and scheme comparison, we put forward a design scheme of 8mm transceiver front-end using LTCC technology.The module is fabricated in the 69mm×51mm×20mm cavity. The experimental results show that, the output power is more than 690mW, and the out-band spurious suppression is better than 40dBc. The gain of receiver is higher than 30dB while the gain flatness is less than 1dB and the noise figure is less than 5.5dB.