PNA-X N5242A的OIP3限制

根据我自己的实验，在这些频率和IFBW设置下，-120 dBm是盒子的本底噪声。
您可以通过减少接收器衰减来降低本底噪声，但信号功率为-15 dBm时，您会看到接收器生成的噪声基底以上的三阶产品。
如果您可以描述您要测试的设备的特性和规格，我们可能会更加具体地了解PNA-X进行所需测量的能力。
此外，我注意到您在FOM模式下使用多个标准通道进行IMD测量。
如果您了解选项087（IMD测量），我很好奇，这将极大地简化您的所有IMD测量需求的设置和校准。



     以下为原文

  Based on my own experimentation, -120 dBm is the noise floor of the box at these frequencies and IFBW setting.  you can lower the noise floor by applying less receiver attenuation, but with -15 dBm signal power, you will see receiver generated 3rd order products above the noise floor.  If you can describe the characteristics and specifications of the device you are trying to test, we might be able to be more specific about the ability of the PNA-X to make the required measurements.  Also, I noticed that you are using multiple standard channels in FOM mode to make your IMD measurements.  I was just curious if you are aware of option 087 (IMD Measurements), which would greatly simplify setup and calibration for all your IMD measurement needs.

正如daras所说，您可以测量的IP3取决于您如何驱动DUT，因此如果PNA的OIP3（使用您的设置）为33 dBm，则限制您可以测量的OIP3是不对的。
如果驱动器值足够高，可以测量非常高的IP3值，以确保* dBc *值高于PNA的限制。
例如，如果你的放大器的OIP3为50 dBm，以+20 dBm输出功率驱动，则IM电平将为-40 dBm;
这是60 dBc，很容易在PNA上测量。
我通常描述的限制是PNA可以测量的最大dBc电平。
根据我的经验，通过仔细的衰减设置，您可以达到85到90 dBc。
这与您在-15 dBm输入功率下的33 dBm值一致，实际上您的结果略胜一筹。



     以下为原文

  Just as daras said, the IP3 that you can measure depends upon how you drive the DUT, so it's not right to say that if OIP3 of the PNA, with your settings, is 33 dBm, it limits the OIP3 that you can measure.  You can measure very high IP3 values if the drive value is high enough to ensure the *dBc* value is above the limit of the PNA.

For example, if you have an amplifier with a OIP3 of 50 dBm, being driven at +20 dBm output power, then the IM level will be at -40 dBm; this is 60 dBc and is easily measured on the PNA.  

The limit that I usually describe is the maximum dBc level that the PNA can measure. With careful attenuation setting, you can achieve between 85 and 90 dBc, in my experience.  This is consistent with you value of 33 dBm at -15 dBm input power, in fact your results are slightly better.