有关Load_Pull

rf9902

各位高手能不能介绍一下什么是Load_Pull？它有什么作用？有没什么好的资料？

RFlw

Loadpull  is actually automated tuner system. It is used tocharacterized  power devices, specially at large signal condition.

As you know, when designing PA, you need to find optimum input andoutput imepdances which satisfied the certain requirements such asVSWR, ouput power, acpr, imd3...

It is also a essential tool for Modeling engineers, since the largesignal model cannot be extracted from only small signal S parametersand DC measurements.

let me know what you are interested, only general concept or somethingspecial. I have a thesis from Chris Liu who invented differentialloadpull system, will upload upon your request.

[br]<p align=right><font color=red>+5 RD币</font></p>

dans_RF

<P>What I am looking for is to understand the concept of LoadPull and learn how to use it in the  power amp design.</P><P>I'd appreciate it for any help. </P>

slienteyes

Can you provide some materials about load pull?

vitou

<P>what u need actually is the load-pull data,which indicate PA's outputpower vs PA's loadimpedence.To get a certain output power ,you need to design a match circuit to transtlate the impedence of the circuit after PA to a specific impedence according to the loadpull data.</P>

songbo0133

loadpull的中文叫做负载牵引，是对射频晶体管尤其是功率管最大输出功率或最优效率或最佳双音互调等特定要求的阻抗参数的一种测试方法。可以用仪器设备实现，可以用仿真软件实现，比如ads。且ads中还有个很好的例子说明loadpull的原理。[br]<p align=right><font color=red>+1 RD币</font></p>

swjll

load pull 中的S11_rho和S11_center的值是根据什么来确定的？它们之间和设计要求的VSWR有没有关系？

songbo0133

load pull中的s11_s11_rho和s11_center的值是通过尝试得到的，对于功率放大器来说输出只考虑输出的功率，不考虑vswr，输入要考虑的[br]<p align=right><font color=red>+1 RD币</font></p>

swjll

<P><b><FONT color=#000066 size=3>谢谢songbo0133的解答</FONT></b></P><P><b><FONT color=#000066 size=3>我还有个疑问：</FONT></b></P><P><b><FONT color=#ee1169 size=3>是不是说先根据器件PDF资料中提供的s22，将此设计频点的s22作为loadpull的s11_center，然后得出一组sample点，再在sample中选取功率和效率都符合设计要求的点b。然后再以b点作为最终设计所需的s11_center？</FONT></b></P>

songbo0133

不需要再选取b了，找到符合要求的点就可以了。在做loadpull图的时候s11_center和r选取的不好的话，负载牵引的等高线不回完全闭合的。

swjll

<FONT size=4><b>难道我选取s11_center点的时候就是用试探法，靠运气去找了？是不是找到的那个点如果登高线闭合的话，此点就符合要求？如果等高线不闭合，此点能不能拿来进行后面步骤的设计？</b></FONT>

zjz_2004

<P>Maybe a load pull measurement system is useful to you.Load pull is<B> </B>a measurement technique in which the Load impedance is modified using a tuner. Part of the signal generated by the device under test (DUT) is returned with a modified amplitude and phase and interacts with the departing signal, modifying its operation (and Gain) in this way. The most usual tuning condition is '<I>matching'</I>, in which case the returned power is zero (the transistor is power matched). </P><P><img src="http://www.focus-microwaves.com/FAQs/IMAGES/lpsetup_small.jpg">
If you have more questions, you could land <a href="http://www.focus-microwaves.com/FAQs/FAQs.htm" target="_blank" >http://www.focus-microwaves.com/FAQs/FAQs.htm</A> or contact with <a href="http://www.step-china.com" target="_blank" >www.step-china.com</A></P>

gogo1222

【文件名】:06712@52RD_LoadPullPres.ppt
【格　式】:ppt
【大　小】:378K
【简　介】:
【目　录】:

Agilent 关于LoadPull的详细PPT[br]<p align=right><font color=red>+5 RD币</font></p>

gogo1222

目前在做一个工作于380MHz 的功放
用负载迁移后的PAE比不用时还小,不知道是啥回事,请高手指点!谢谢!

leletian

谢谢楼主分享！[em01][em01]

agan

我也了看，就是没有看懂这load pull ，哎，谁有实例中文的发来see see 才好

sunnu789

http://www.52rd.com/bbs/Detail_RD.BBS_168928_26_1_1.html
有原理和局限.