如何计算ST25R3911B中读数的分压电容值？

你好Prashanth，
 
电容分压器用于将天线上的一小部分电压反馈到ST25R3911B的接收器输入引脚。 V_RFI的计算方式如下：
（假设电容分压器10：150）
 
现在有两种简单的方法可以获得你的V_ANT。
1.）您可以在“ST25R天线匹配工具”（Save＆amp; Simulate）中使用模拟内置。
在那里，您还可以调整电容分压器并查看其影响。
2.）将估计的匹配元件组装到读卡器板上并测量天线上的电压。
 
在进行匹配元件的计算时，您是否考虑过电容分压器？它与并联调谐电容并联，因此增加了9到10 pF。 （根据比例）
我们的工具已将此考虑在内，因此您和我们的计算非常适合。
 
BR Travis



以下为原文

Hello Prashanth,

The capacitive voltage divider is to feedback a fraction of the voltage on the antenna to the receiver input pins of the ST25R3911B. V_RFI is calculated like this:

(Assuming a capacitive voltage divider 10:150)

There are now two easy ways to get your V_ANT.
1.) You use the build in simulation in the "ST25R Antenna Matching Tool" (Save & Simulate).
There you can also adjust the capacitive voltage divider and see its influence.
2.) You assemble the estimated matching components to your reader board and measure the voltage across the antenna.

When doing the calculation of the matching components, have you considered the capacitive voltage divider? It is put in parallel of the parallel tuning capacitor and therefore adds additional 9 to 10 pF. (according to the ratio)
Our tool already takes this into account and therefore your and our calculation would fit quite well.

BR Travis