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随着模数转换器(ADC)采样频率的提高,保证其电压采样精度成为封装设计中的难题。完成了一款采样频率为3 GHz的ADC陶瓷外壳的设计,根据设计规则及EDA软件仿真结果,确定ADC外壳的层叠结构及走线,使阻抗有较好的匹配性,降低信号反射;使用全波电磁场分析软件对不同材料、不同直径键合丝的传输特性进行了仿真,对关键信号放置在不同层情况下的插入损耗进行分析对比,选择符合工艺条件的最优方案。仿真结果表明该设计达到了3 GHz ADC的外壳设计要求,但实际测试结果与仿真结果有一定误差,测试用印刷电路板(PCB)的插入损耗可能是导致差异的一个重要原因。
As the sampling frequency of an analog-to-digital converter (ADC) increases, ensuring the accuracy of voltage sampling becomes a challenge in package design. The design of an ADC ceramic shell with a sampling frequency of 3 GHz was completed. According to the design rules and the simulation results of EDA software, the cascaded structure and traces of the ADC shell were determined to make the impedance better matched and reduce the signal reflection. Wave electromagnetic field analysis software was used to simulate the transmission characteristics of bond wires with different materials and different diameters. The insertion loss of key signals placed in different layers was analyzed and compared, and the optimal scheme was selected according to the process conditions. The simulation results show that the design meets the design requirements of the 3 GHz ADC. However, the actual test results have some errors with the simulation results. The insertion loss of the printed circuit board (PCB) may be an important cause of the discrepancy.