N8975A输入损耗校正表未按预期工作

输入损耗校正功能，Fixed，Table，Temp没有给出我预期的结果。
我正在测试16Ghz 16db增益放大器，预期噪声系数为1.7db。
我正在使用输入损耗表来校正电缆和探头损耗。
16Ghz的输入损耗为1.2db。
输出丢失表条目大约是0.5db。
将输出探头连接到NFA的电缆包含在用户校准中。
仪表测量的增益为16db，与我的s参数测量相匹配。
噪音系数为2.3db。
输入损失的1/2是高于预期的数字。
如果我关闭输入损耗校正，噪声系数会增加0.6db到2.9db，增益会减少1.2db。
增益下降是预期的，但噪音应该上升！
由1.2db不是0.6db！
我尝试了另一种自我一致性检查，并在噪声源和放大器之间放入一个3db垫。
保留输入损耗补偿表。
我看到噪声系数上升了3db到5.3db，增益下降了3db，如预期的那样。
现在我将3db添加到输入损失补偿表中的值。
正确计算增益为16db但噪声为3.8db ...仅从计算出的噪声系数中删除1.5db！
为什么噪声系数只能通过我输入损耗补偿系统的输入损耗的1/2来校正？
如果我使用旧学校方法通过将ENR值降低1.2db来校正额外损失，我会得到我期望的增益和噪声系数！编辑：malibu于2013年4月25日下午10:55



     以下为原文

  The input loss correction functions, Fixed, Table, Temp are not giving me expected results.  I am testing a 16Ghz 16db gain amplifier with expected noise figure of 1.7db.  I am using an input loss table to correct for cable and probe losses.  The input loss at 16Ghz is 1.2db.  The output loss table entry is about 0.5db.  The cable connecting the output probe to the NFA was included in the user Calibration.  The meter measures gain of 16db which matched my s-parameter measurement.  The noise figure comes out at 2.3db. A figure that is 1/2 of the input loss above what is expected.  If I turn off the input loss correction the noise figure increases by 0.6db to 2.9db and the gain decreases by 1.2db.  The gain decrease is as expected but the noise should have gone up! by 1.2db NOT 0.6db!  I tried another self consistency check and put in a 3db pad between the noise source and my amp.  Leaving the input loss compensation table on.  I see the Noise Figure go up by 3db to 5.3db and the gain go down my 3db as expected.  Now I add 3db to the values in my input loss compensation table.  

The gain is correctly computed to be 16db but the noise is 3.8db... only 1.5db is removed from the computed noise figure!

Why is the noise figure only being corrected by 1/2 the input loss that I put in to the loss compensation system?

If I use the old school method of correcting for additional loss by reducing the ENR value by 1.2db I get both gain and noise figure numbers I expect!

Edited by: malibu on Apr 25, 2013 10:55 PM