A Study On Microwave Passive Component Based On LTCC Technology

To achieve a compact high-performance circuit, passive components such as inductors and capacitors are embedded in the medium of low temperature co-fired ceramic(LTCC) technology, meanwhile, reducing the production cost as well. This paper research on microwave passive components based on LTCC technology, and the author carries out the work mainly in the following three aspects:1. During modeling lossless transmission line, simulate lossless transmission line and its equivalent circuit model respectively. It can be seen clearly that S curves of T equivalent model and lossless transmission line fit better in 2 GHz bandwidth, however, it has greater deviation with higher frequency. To make equivalent model universal, propose a new revised model based on original T model, and a specific parameter extraction method is given. Simulating improved equivalent model in ADS to get scattering parameter S curve, it can be discovered that revised model is applicable in bandwidth up to 5 GHz by comparing S curves of new model and lossless transmission line, which is useful in circuit design.2. During modeling LTCC planar spiral inductor, firstly, propose the single π equivalent circuit model based on the structure of LTCC inductor and extract circuit parameters by Y admittance matrix. It can be discovered that S curves of inductor in HFSS and circuit model in ADS fit better in 1 GHz bandwidth, however, it has greater deviation with higher frequency and cannot applied in wideband analysis. Taking the skin effect at high frequency into account, so propose revised π equivalent circuit of planar spiral inductor. It contains coupling capacitance between the inductors, parasitic resistance, resistance and inductance induced by skin effect. And a specific parameter extraction method is given, the simulation results show that the equivalent circuit model can simulate the inductor, S curves also can coincide in a bandwidth up to 3 GHz, meanwhile, verify that circuit component parameters such as effective inductor value and coupling capacitor value extracted by the model is right. These parameters have a certain reference value for LTCC spiral inductor design.3. During modeling LTCC vertically interdigitated capacitor, firstly, propose the single π equivalent circuit model and extract component parameters based on circuit structure. After simulation, it can be discovered that the model can imitate capacitor in 3 GHz bandwidth by comparing S curve, but it has a greater deviation beyond that frequency and cannot be applied in wideband analysis. So put forward a improved equivalent circuit and this revised π equivalent structure uses two resistances to represent medium loss and conductor loss respectively for the reason they have different effect on circuit. At the same time, introduce input and output inductors in circuit to make equivalent network coincide with real circuit. Considering the structure of capacitor equivalent circuit and optimization function of ADS software, gain the scattering parameter S after the simulation, and the results show this equivalent circuit model can better imitate capacitor working condition, two curves can coincide better in 5 GHz bandwidth as well. The above can verify parameters extracted by the modified model is effective and broaden the scope in which equivalent model can apply.