Design Of Chip-type Filter With Different Materials Based On LTCC/LTCF Technology

With the development of modern microwave communications,particularly in satellite communications and mobile communications, the system increases the selectivity of the channel and puts forward higher requirements on the design of microwave filter. The performance of microwave filter as an important part of the communication system, determines the quality of microwave communication system. So the study and design of microwave filter design is very important.A low pass filter and two band-pass filters are designed with ceramic substrate and ferrite substrate based on LTCC technology. For the need of design of high frequency circuits, the structures of LTCF lumped inductors and LTCC lumped capacitors are established in the three-dimensional electromagnetic simulation software HFSS. Their equivalent-circuit models are obtained and analyzed. Through the analysis of lumped inductors and capacitors effective values and Q values, a method to optimize the lumped inductors and capacitors performance is obtained. After simulated when the structure parameters change, the effective value and Q values of the capacitor and inductor are found.According to the method of Insertion loss, the appropriate capacitors and inductors in the establishment of the LTCF lumped inductor and LTCC lumped capacitor models are chosen, the layout of the lumped inductors and capacitance is optimized, a low-pass anti-EMI filter with the cutoff frequency of 10MHz is designed, insertion loss less than 0.5dB in passband, above 40dB attenuation gain at 50MHz. The volume of the whole structure is 3.2mm×1.2mm×0.6mm.Two three-order Chebyshev lumped element band-pass filters are designed and their structure parameters are optimized, based on the principle of band-pass filters. The volume of the filter is 4.8mm×2.4mm×1.2mm. The bandwidth of the 68MHz capacitors coupled band-pass filter is 8MHz, insertion loss less than 1dB in passband, and with good band rejection characteristics; the bandwidth of the 10MHz capacitors coupled band-pass filter is 1.6MHz, insertion loss less than 1dB in passband, and also with good band rejection characteristics.