关于信号发生器信号源的一些基本问题

欢迎提出任何意见或建议，非常感谢



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  Any comments or advice is welcome,

thank you very much

还在等待帮助。
非常感谢



     以下为原文

  still waiting for help. 

thanks alot

嗨Yiliu - 基本上所有放大器 - 包括信号发生器中的放大器 - 将在上部（压缩）范围内具有非线性部分。
当自动调平环无法成功保持输出水平时，会出现不平衡的情况。
如果输出电平设置太高，可能会发生这种情况。
如果您的设备正在输出非调制信号并显示不平衡但未超过规定的功率限制，那么我怀疑可能在某处内部发生故障。
从你的例子来看，似乎你正在寻找两种获得15dBm输出的方法：（a）SG 400MHz，输出= 15dBm（b）SG 400MHz，输出= -25dBm，加上40dB功率放大器你是对的，
选择真的取决于你所追求的表现。
如果您的信号发生器的最大功率输出为15dBm，但性能（频谱纯度）在高功率下会充分降低，那么您可能需要使用外部放大器 - 前提是外部放大器的性能符合您的要求。
以下是一些可能很重要的规范：频率响应输入功率要求谐波性能IMD等......这些都可以使用频谱分析仪进行检查。
问候 -



     以下为原文

  Hi Yiliu -

Basically all amplifiers – including those found in signal generators - will have a non-linear portion in the upper (compression) range.  Unleveled conditions occur when the automatic leveling loop cannot successfully keep the output leveled. This can happen if the output level setting is too high. If your unit is outputting a non-modulated signal and displaying unleveled, but not exceeding the specified power limit, then I would suspect that maybe there is malfunction somewhere inside.

From your example, it seems that you are looking at two methods in which to obtain a 15dBm output:
(a) SG 400MHz, output=15dBm
(b) SG 400MHz, output=-25dBm, plus a 40dB power amplifier

You are correct, the choice really depends on the performance that you are after.

If your signal generator has a power out maxinum of 15dBm, but the performance (spectral purity) is degraded sufficiently at high power, then you might want to go with an external amplifier – provided that the external amplifier performance meets your requirements.

Here are some specifications that might be important:
Frequency response
Input power requirement
Harmonic performance
IMD, etc…

These can all be checked with a spectrum analyzer.

Regards -

谢谢tabbott。
我可以总结如下：对于PA，如规范中所述。
表，有谐波/泛音，P1dB。
对于SG，可以通过频谱分析仪确认非线性/失真性能。
BR，伊柳



     以下为原文

  thanks tabbott.

Can I summarize as the following:

For PA, as in the spec. sheet, there is the harmonics/overtone, P1dB.

For SG, the non-linear/distortion performance can be confirmed by the spectrum analyzer.

BR,
Yiliu

嗨伊柳 - 我不太清楚你的意思是“谐波/泛音”。
但总的来说，在两种情况下（PA或SG）都可以通过频谱分析仪确认非线性性能。
你的PA是正确的，P1dB通常可以在数据表中找到。
对于SG来说，它会变得有点复杂，因为大多数SG都会有一个ALC电路，它试图确保在指定范围内进行线性操作。
为了确认P1dB点，您需要禁用ALC并将功率调整到最大值。
问候 -



     以下为原文

  Hi Yiliu -

I’m not quite sure what you mean by “harmonics/overtone”. 

But in summary non-linear performance can be confirmed by the spectrum analyzer in both cases (PA or SG).

You are correct in that for PA’s, P1dB can usually be found in the data sheet. 

For the SG it gets a bit more complicated as most SG’s will have an ALC circuit that tries to ensure linear operation over the specified range. 

In order to confirm the P1dB point you would need to disable the ALC and adjust the power toward maximum.

Regards -

嗨，塔博特，我很抱歉打字错误。
它应该是谐波，而不是谐波/泛音。
仅供参考，附件是PA规格。
表格，由R＆amp; K.



     以下为原文

  Hi, tabbott,

I am sorry for the typo.

It should be harmonics, not harmonics/overtones.

FYI, attached is one PA spec. sheet, which is by R&K

附件

• Amplifier_A00110-4040-R.pdf151.0 KB
  

嗨伊柳 - 谢谢你清理这个。
SG的性能规格也可以在数据表中找到。
例如，电源精度，E8257D的谐波性能可在以下数据表中找到：http：//cp.literature.agilent.com/litweb/pdf/5989-0698EN.pdf此外，我们的服务文档提供了验证的程序
（使用频谱分析仪等）指定的性能。
问候 -



     以下为原文

  Hi Yiliu -

Thanks for clearing this up. Performance specifications for the SG can also be found in the data sheets. For example power accuracy, harmonic performance for the E8257D can be found in the following data sheet:
http://cp.literature.agilent.com/litweb/pdf/5989-0698EN.pdf

In addition, our service documentation provides procedures to verify (using spectrum analyzers, etc…) the specified performance.

Regards -