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qiuyangdvb
Joined: 04 Apr 2008
Posts: 4
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 04 May 2008 11:25 help me about power amplifier! |
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I want to use a eudyna power transistor,
but there is no big signal load /source impedance ,
only s parameters in the datasheet,can I use it to match?
I think S parameter is small signal.
what shall I do?
thank you!
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FvM
Joined: 22 Jan 2008
Posts: 1827
Helped: 332
Location: Bochum, Germany
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| 04 May 2008 11:40 Re: help me about power amplifier! |
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| S-parameters for power transistors are given for an operation point of a typical application. This is the case e. g. with Polyfet data. So, if the operation point in the data sheet is similar to your application, regarding both DC bias and transmitted power, you can use it to design impedance matching.
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qiuyangdvb
Joined: 04 Apr 2008
Posts: 4
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| 10 May 2008 5:21 Re: help me about power amplifier! |
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but the S-parameters are given only for the DC bias point .
there is no output power ,
can I use it?
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VSWR
Joined: 07 Feb 2002
Posts: 608
Helped: 50
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| 10 May 2008 10:48 Re: help me about power amplifier! |
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Using S-parameters of the transistor, it is only possible so simulate small signal/linear behaviour of the amplifier. For example linear gain. To simulate non-linear properties, such as RF output power, 1 dB compression point, OIP3, etc a non-linear (SPICE) model of the transistor is required in the simulations.
Contact the transistor manufacturer for availability of a SPICE model of the transistor. In most cases it's available upon request, even if it's not presented in the data sheet or on the web.
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ivanrb
Joined: 12 Jun 2006
Posts: 3
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| 12 May 2008 9:59 Re: help me about power amplifier! |
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First of all you can ask Eudyna to supply you with more data for the transistor you have chosen. For some of their transistors they have load-pull impedances data and if you are insistent enough and if they decide that you’re important for them they can provide you with more data.
I have some of their transistor load-pull data and I can send it to you. Which transistor you have in mind? Ivan.boshnakov(at)axellwireless.com
On the other hand if your design will be at the same bias point (or close) you can use S-parameters as a starting point to design power amplifiers. You need to use the Cripps load-line approach. There are a couple of books from him. Basically you fit a linear model of the transistor to the S-parameters. Then using the limits of the voltages and currents of the transistor you can extract the intrinsic optimum load-line and the corresponding impedance for the maximum P1dB and even the load-pull contours. The best way to do this is to use a software program called MultiMatch. There is an article that explains how this software will help you to design power amplifiers using only S-parameters. http://radarcafe.com/documents/First-Time-Right_Design_of_RF-Microwave_Amplifiers_-_copyright.pdf
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designtech
Joined: 09 Feb 2006
Posts: 52
Helped: 2
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| 16 May 2008 3:23 Re: help me about power amplifier! |
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| Usually input matching would be based on small signal only.
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tyassin
Joined: 22 Jul 2004
Posts: 228
Helped: 27
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| 16 May 2008 9:52 Re: help me about power amplifier! |
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Too ivanrb
A minor interruption 
How much is a single licens for MultiMatch?
Regards
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ivanrb
Joined: 12 Jun 2006
Posts: 3
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| 16 May 2008 17:42 Re: help me about power amplifier! |
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| You should go to www.ampsa.com, get the contact info from there and ask for quotation. There are a lot of variations and options. But let's say about $20000 for full capabilities. If you design amplifiers regularly you’ll not regret having the software.
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Andrew77
Joined: 16 Mar 2006
Posts: 12
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| 16 Jul 2008 9:25 help me about power amplifier! |
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Hi ivanbr,
I'm developing a 2-2.7 GHz Power Amplifier of 30 or more dB of gain by using Eudyna devices such as: FLL357ME and FLL810IQ-3C. I'have read that you have Source/Load pull data of some eudyna devices, could you send them to me? ag001(at)inwind.it
Thanks
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