L-band Ltcc Transceiver Front-end Research

With the development of electronic technology, the demand about the volume, performance and cost of electronic systems becomes more and more strict. So the microwave integrated circuits in communication, radar, navigation, control systems seek a development of miniature size, higher performance but lower cost. LTCC (Low-Temperature Co-fired Ceramic) technology makes multi-layers construction to form a three dimensional, high-density substrate, with the low insertion loss in high frequency and easy to integrate, LTCC has become a hot research branch towards high density integration.The thesis Firstly gives a brief introduction to LTCC technology and its corresponding productions and applications. Under this background the following work is taken:1,Take the advantage of LTCC technology to design compact passive circuits. Depent on capacitors and inductors in LTCC, using J/K convertors and couping theory, various compact L/C filters with targeted zeros are synthesized. Among the L/C filters, the thesis proposes an ultra-narrow band band-pass filter with two transmission zeros, the measured results show the filter having a good performance of high suppression in stopband. Thus, an improved compact five layers folded comb-line filter with cross-coupling is present too, the filter has a sharp stop band and the measured results show an excellent performance. Based on FSIW resonators, H-Plane FSIW filters in X-band are simulated and the analyses about the suppression in stopband are gave meanwhile.2,Finally, the aim of this thesis is to design two kinds of front-end system in L-band, one is that all the band-pass filters in the front-end system are embedded, another is that the corresponding filters are designed to signal curcuits, then welded on the substrate. A double frequency conversion schematic is chose to depress the imagine frequency in both of the front-end systems. In order to reduce the size, the receiver and transmitter use common LOs. The whole size of the front-end system is 60×44× 10mm3, and the tested results show both the front-end systems are compact and high spurious frequency rejection.The measured results of the front-end system with filters welding on the substrate surface show that the transmitter power is bigger than 1.5dBm, the worst spurious frequency rejection is better than 33dB, the receiver has a gain of 26.5±2dB, spurious frequency and image frequency rejection are both better than 40dB, and noise figure is smaller than 7dB, meet the design targets basically. And the other one except the amplitude of transmitter power becoming worst in the lower sideband of RF, other measured results are nearly same with the first one.