LTCC带通滤波器中心频率偏移的优化

Optimization for the Center Frequency Deviation of LTCC Band-Pass Filter

针对某型号LTCC带通滤波器产品中心频率往低频方向偏移了约50 MHz的问题展开研究。根据中心频率公式推测出可能导致中心频率偏移的工艺指标为电感线宽精度、介质层厚度、层间对位精度。对滤波器样品进行剖切、测试,提取这些工艺参数,然后在HFSS仿真软件中进一步分析这些参数对该滤波器模型中心频率的影响,最终确认导致滤波器中心频率偏移的关键因素为电感线宽偏差。对电感线宽进行纠偏,使产品中心频率等工艺指标与设计值相统一,最终使产品中心频率的偏移由50 MHz优化到5 MHz。

This paper was aimed to analyze the center frequency deviation of about 50 MHz towards low frequency in the LTCC band-pass filter. According to the center frequency formula, the technical indexes： the inductor line width, the dielectric layer thickness and the layer-to-layer positioning accuracy may be responsible for this skewing. These indexes value were then extracted by slicing the sample and further analyzed in HFSS to measure their influence on the center frequency of the band-pass filter. And deviation of the inductor line width was diagnosed as the main culprit for this divergence. The optimization of the center frequency from 50 MHz to5 MHz was eventually attainable by adjusting the inductor line width and rendering the technical index consistent with its design value.