怎么使用网络分析仪测量输入参考噪声

通过PNA-X（028或029）上的任一噪声系数选项，您可以测量设备的冷源（输入端接）噪声功率，您当然可以测量增益，因此任何输出端口功率都可以参考
输入。
PNA-X上的噪声系数应用提供以下参数（除50欧姆噪声系数外）：*噪声功率参数：* ---------------- * _SYSNPD / SYSNPDI_
* - 系统噪声功率密度：ADC的总噪声功率，包括DUT和内部噪声接收器产生的噪声。
这通常表示为以dBm为单位的绝对功率测量值，但也可以以瓦特或开尔文表示。
dBm = 10 log10（k * T * B * 1000）其中：k =玻尔兹曼常数T =测得的噪声温度B =带宽1000 =从毫瓦转换* _SYSRNP / SYSRNP_ * I - 系统相对噪声功率：噪声温度
DUT和接收器的组合相对于290开尔文。
这通常报告为以dB为单位的比率。
因此，完美安静的设备会产生0 dB的迹线。
dB = 10 log10（T / 290）* _DUTNPD / DUTNPDI_ * - DUT噪声功率密度：当校正为ON时，此迹线显示可用的噪声功率，最佳描述为DUT中可用的最大功率，其中噪声端口的阻抗
等于DUT的输出匹配。
更确切地说，当噪声端口匹配等于DUT的输出匹配的共轭时，会发生这种情况。
由接收器贡献的噪声功率被移除。
当校正为OFF时，迹线显示更准确地描述为输出功率。
交付的功率是ADC实际看到的功率。
接收器和DUT之间的任何不匹配都将被忽略。
由接收器贡献的噪声功率被移除。
该测量值通常以dBm表示：dBm = 10 log10（（DUT温度 - 接收器温度）* B * 1000）其中：B =带宽1000 =从毫瓦转换* _DUTRNP / DUTRNPI_ * - DUT相对噪声功率：此测量值呈现
作为DUT温度与290开尔文的比率。
它通常以dB表示。
如上所述，对于DUTNPD，相同的评论适用于可用功率与输出功率。
dB = 10 log10（DUT温度 - 接收器温度）----------------------如果您提供有关您的设备的更多信息（增益，预期噪声系数，...
。）我们可以帮助您确定哪种噪声系数选项（028或029）适合您的应用。



     以下为原文

  with either of the noise figure options on the PNA-X (028 or 029), you can measure the cold source (input terminated) noise power of your device and you can certainly measure gain, so any output port power can be referred back to the input.  the noise figure application on the PNA-X provides the following parameters (in addition to the 50 Ohm Noise Figure):

*Noise Power Parameters:*
----------------

*_SYSNPD / SYSNPDI_* - System Noise Power Density:  Total noise power available at the ADC, including the noise contributed by both the DUT and the internal noise receiver.  This is generally expressed as an absolute power measurement in dBm, but can also be expressed in Watts or Kelvin.   

dBm = 10 log10(k * T * B * 1000)
 
where:
  
 
 
k = Boltzmann's constant
 
 
T = the measured noise temperature
 
 
B = bandwidth
 
 
1000 = conversion from milliwatts
 

*_SYSRNP / SYSRNP_*I - System Relative Noise Power:  The noise temperature of the combined DUT and receiver relative to 290 Kelvin.  This is generally reported as a ratio in dB.  Therefore a perfectly quiet device would render a trace at 0 dB. 

dB = 10 log10(T/290)

*_DUTNPD / DUTNPDI_* - DUT Noise Power Density:  When correction is ON, this trace exhibits the available noise power, best described as the maximum power available from the DUT where the impedance of the noise port is equal to the output match of the DUT. To be more precise, this occurs when the noise port match is equal to the conjugate of the output match of the DUT.  The noise power contributed by the receiver is removed.

When correction is OFF, the trace exhibits what is more accurately described as delivered power.  Delivered power is the power actually seen by the ADC.  Any mismatch between the receiver and the DUT is ignored.  The noise power contributed by the receiver is removed.

This measurement is generally expressed in dBm:

dBm = 10 log10( (DUT Temperature - Receiver Temperature) * B * 1000)
 
where:
  
 
 
B = bandwidth
 
 
1000 = conversion from milliwatts
 

*_DUTRNP / DUTRNPI_* - DUT Relative Noise Power:  This measurement is rendered as a ratio of the DUT temperature to 290 Kelvin.  It is generally expressed in dB.  The same comments apply with respect to available versus delivered power as described above for DUTNPD.

dB = 10 log10 (DUT Temperature - Receiver Temperature)
----------------------

If you provide more information about your device (gain, expected noise figure, ...) we can help you decide which noise figure option (028 or 029) is appropriate for your application.

嗨Daras，感谢您的回复，我不认为噪声功率和输入参考噪声之间有任何直接联系。
他们是一样的东西吗？
dBm和pA / square_root_Hz的读数是不同的。



     以下为原文

  Hi Daras,

thanks for your reply, i don't see there si any direct connection between noise power and input referred noise.

are they the same things? the readings in dBm and pA/square_root_Hz are different.

我想这取决于您使用的“输入参考噪声（IRN）”的定义。
我不得不承认，这是我第一次遇到这个术语，不得不做一些挖掘才能理解它。
根据UCLA（_Noise PDF_）中的EE课程，“输入参考噪音”的定义如下：https：//dl.dropbox.com/u/87949221/InputReferredNoise.jpg！
因此从这个定义可以推断出输入噪声只是输出噪声功率（或电压）除以电路的增益。
此定义的另一个来源是_blog_，它正确地指出可以测量的唯一噪声是输出噪声。
因此，IRN只能通过输出噪声功率和增益的某些测量来计算。
IRN的实际配方将取决于您对它的确切定义。
对于“pA / square_root_Hz”的单位，我猜测得到的噪声功率被归一化到带宽并以某种方式转换为安培，并且再次取决于所使用的确切定义。
编辑：daras于2013年1月14日下午6:35编辑：daras于2013年1月14日下午6:37



     以下为原文

  I suppose that depends on the definition of "Input Referred Noise (IRN)" that you are using.  I have to admit that this is the first time I've come across this term and had to do some digging to understand it.  According to what appears to be a EE course hand out in UCLA (_Noise PDF_), the definition for "Input Referred Noise" is the following:

!https://dl.dropbox.com/u/87949221/InputReferredNoise.jpg!

so from this definition one can deduce that input noise is simply output noise power (or voltage) divided by the gain of the circuit.  Another source for this definition is this _blog_ and it correctly states that the only noise that can be measured is output noise.  So IRN can only be computed from some measurement of output noise power and gain.  the actual formulation of IRN would then depend on your exact definition for it.  As for the units of  "pA/square_root_Hz", my guess is that the resulting noise power is normalized to the bandwith and somehow converted to amps and again that would depend on the exact definition being used.  

Edited by: daras on Jan 14, 2013 6:35 PM

Edited by: daras on Jan 14, 2013 6:37 PM

是的，Dara是完全正确的。
我们可以测量放大器（或任何电路）的噪声功率。
传输阻抗放大器的问题在于它具有输入电流和输出电压，因此计算功率测量的增益（这都是VNA可以做到的）有点棘手。
因此，假设您可以测量DUT的S参数和输出噪声功率（即，噪声功率为50欧姆负载，W / Hz，增益从50欧姆源到50欧姆负载）。
我们可以轻松衡量。
那么，为学生练习：如何在输出到50欧姆负载时测得的噪声功率和测量增益，以pA / Hz计算输入噪声功率？
请出示你的作品......



     以下为原文

  Yes, Dara is exactly right.  We can measure noise power from an amplifier (or any circuit).  The trouble with a trans-impedance amplifier is that it has as an input current and an output is voltage, so computing the gain from power measurements (which is all a VNA can do) is slightly tricky.

So, presume you can have the S-parameters of the DUT measured, and the output noise power (that is, noise power into 50 ohm load, in W/Hz, and gain from a 50 ohm source to a 50 ohm load).   We can easily measure that.

So, exercise for the student: how to compute input noise power in pA/Hz given measured noise power at the output into a 50 ohm load, and measured gain?  

Please show your work...

大家好，感谢您的帮助。
我想我知道答案。
输入电流可以根据输入功率计算，除以放大器的带宽（我假设是起始 - 停止频率）和宾果，我得到了uA / Hz。
如果带宽使用NA的IFW，请告诉我。
再次感谢大家的参与。
安捷伦论坛是最好的。



     以下为原文

  hi all,

thanks for your help.

i guess i know the answer.

the input current can be calculated from input power, and divided by the bandwidth of amplifier ( i presume is the starting - stop frequency )

and bingo, i got the uA/Hz.

if the bandwidth are using the IFW of NA, please let me know.

thanks again for everyone participation. Agilent forum is the best.

VNA已经以W / Hz噪声功率密度显示噪声功率。
因此，您只需要通过跨阻抗增益将输出端的W / Hz转换为输入端的A / Hz。
如果您有总噪声功率（我们没有显示），您将使用噪声测量BW，通常为4 Mhz。
但是没有必要，我们的噪声功率密度函数处理BW标准化。



     以下为原文

  The VNA already display noise power in W/Hz noise power density.  So you just need to convert W/Hz at the output to A/Hz at the input through the transimpedance gain.  

If you had the total noise power (which we don't show) you would use the noise measuerment BW which is typically 4 Mhz.  But no need, our noise power density function handles the BW normalization alread.