[问答]

边缘电容多项式的系数

问答对人有帮助，内容完整，我也想知道答案 0 嗨，我正在开展一个需要表征SOLT校准套件的项目。该套件代表从3.5mm SMA连接器到长度为20mm的微带线的过渡。对3GHz以上频率的测量需要将开放边缘电容模型化为3阶多项式。我执行以下步骤：在测试电缆末端进行1- 1端口校准（85033D校准套件）。 2-连接短标准（20mm 50欧姆微带线由2个并联的50欧姆电阻器结束）并使端口扩展直到180度相移。 3-断开短标准并连接开放标准。 4-调整延迟直到相位为负（整个波段的负相位）。 5-提取格式化的RI数据并跟踪并行电容值作为频率的函数。 6-使用数学工具拟合图形以评估电容多项式的系数。注意，如果我们想要整个工作频带的负相位，则开路相位线路既不是平坦的也不是线性的，并且在频带末端（6 GHz）达到-28度。我的问题是电容多项式的系数值很大。（C0 = 38.33E-15; C1 = 79676.1E-27; C2 = -35687.91E-36; C3 = 4270.35E-45）。 VNA不接受超过10000或小于-10000的值。实际上，我试图将乐队划分为两个子乐队，但同样的问题也会出现。此外，我试图最小化频带以实现平坦相位（小于1度的变化），但也出现同样的麻烦。谢谢你的帮助。以上来自于谷歌翻译以下为原文 Hi, I'm working on a project that needs the characterization of a SOLT calibration kit. The kit represents a transition from 3.5mm SMA connector to a microstrip line of length 20mm. The measurement for frequencies above 3GHz requires the modelization of the open fringing capacitance as a polynomial of order 3. I perform the following steps: 1- 1-port calibration at the end of the test cable (85033D calibration kit). 2- Connect short standard (20mm 50ohm microstrip line ended by 2-parallel 50ohm resistors) and make port extension until 180 degrees phase shift. 3- Disconnect short standard and connect the open one. 4- Adjust the delay until the phase is negative (Negative phase across the whole band). 5- Extract the formatted RI data and trace the parallel capacitance values as a function of frequency. 6- Use mathematical tool to fit the graph in order to evaluate the coefficients of the capacitance polynomial. Note that the open phase trace is neither flat nor linear and reaches -28 deg at the end of the band (6 GHz) if we want negative phase for the whole operating band. My problem is that the values of the coefficients of the capacitance polynomial are big. (C0=38.33E-15; C1=79676.1E-27; C2=-35687.91E-36; C3=4270.35E-45). The VNA doesn't accept values more that 10000 or less than -10000. Actually, I tried to divide the band into two sub-bands, but that same problem results. Moreover, I tried to minimize the band in order to achieve flat phase (less than 1 deg variation) but also the same trouble arises. Thanks for your help. 0
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答案对人有帮助，有参考价值 0 频率爱好者，考虑到Joel在“使用9 GHz 3.5 mm校准套件进行20 GHz校准有多糟糕？”这一主题中对我的问题的回答，看起来使用额定为9的次优固定负载的效果 GHz而不是滑动负载不会产生太大影响，因为负载中的错误将与SMA连接器的错误一起被门控。因此，如果您想要使用9 GHz校准套件在具有TDR功能的20 GHz VNA上测量某些东西，请告诉我，我会看到我能做些什么。您需要与您的主管明确这一点。但就个人而言，当我监督学生时，如果有人来找我并说他们可以访问的设备无法进行测量，但是其他人有设备能够做到这一点，那么如果他们能得到它我会毫无异议它在外面完成。我个人认为这是一个积极的步骤，而不是一个消极的步骤，但不同的主管可能对其他人进行测量采取不同的态度。学术界可能很有趣！我的经验是数学家比其他大多数人更多！戴夫以上来自于谷歌翻译以下为原文 Frequency Lover, given Joel's answer to my question in the thread "How bad would a calibration to 20 GHz be using a 9 GHz 3.5 mm cal kit?", it would appear that the effect of using a sub-optimal fixed load rated to 9 GHz, rather than the sliding load, would not have much effect as the errors in the load will be gated out along with errors from the SMA connector. So if you want something measured on a 20 GHz VNA with the TDR function using a 9 GHz cal kit, let me know and I'll see what I can do. You would need to clear that with your supervisor though. But personally, when I supervised students, if one came to me and said the equipment they had access to was not capable of making a measurement, but someone else had equipment able to do it, then I would have had no objections if they could get it done outside. Personally I would have seen that is a positive step, rather than a negative one, but different supervisors might take different attitudes towards someone else making a measurement. Academics can be a funny lot! My experience is mathematicians more than most others! Dave

2019-5-8 16:27:01 评论举报李青

答案对人有帮助，有参考价值 0 更重要的是，如果你不能让SMA连接器足够可重复以消除它们对开路/短路/负载的影响（并且测量开路负载应该显示是否去除了纹波），那么你就不能使用这些不可重复的 SMA连接器可以获得您想要表征的SMT元件的有效测量值。根据我的经验，你可以做这种SMA到PCB适配器和表征到大约-25到-30 dB（大约5％到3％的误差）到大约3 GHz左右的水平，可能会延伸到6 GHz。除此之外，除非采取极端谨慎措施，否则不一致将完全占主导地位。以上来自于谷歌翻译以下为原文 More to the point, if you cannot get the SMA connectors to be sufficiently repeatable to eliminate their effects on the open/short/load (and measuring open-load should show if the ripple is removed or not), then you cannot use these unrepeatable SMA connectors to get valid measurements of the SMT components you wish to characterize. In my experience, you can do this kind of SMA to PCB adapter and characterization to a level of about -25 to -30 dB (about 5% to 3% error) up to 3 or so GHz, maybe stretching to 6 GHz. Beyond that, the inconsistencies will completely dominate unless extreme care is taken.

2019-5-8 16:33:55 评论举报孔德羲