How to get 50ohm match at both frequencies in dual-band LNA?

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rittu

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Dual-band LNA

Hello,
I am working on a dual-band LNA. I have designed it for 802.11a(5.25GHz) and 802.11b(2.45GHz). This is a concurrent LNA which matches to 50 ohms at both 2.45GHz and 5.25GHz. The problem I am facing is that when I consider the pin parasitics of the package (TQFP) The matching at the input of the LNA is seriously disturbed. In single band LNA the pin parasitics which include a capacitor(200-500fF) is tuned out at the single frequency of interest using an external inductor. Since my application requres tuning at both the frequencies I cannot use this technique. Can anyone help me out in this matter. How can I get a 50ohm match at both the frequencies including the pin parasitics.
Thanks in advance
Rittu
 

Dual-band LNA

an idea is to use the switch by mems on the difference component in the two match network.
especial in the out put stage.
 

Re: Dual-band LNA

Maybe the correct answer is: use another package! (QFN).
In fact, in my experience, even at 2GHz you'll need a detailed (HFSS simulated) model of the package and TQFP is not the best choice. At 5GHz this is mandatory.
So, if you try to reduce the package parasitics using for example a QFN one you'll face less problems.

Mazz
 

Dual-band LNA

Thanks a lot for your replies. Can you please tell me more about HFSS. Also my IC has a requirement of 128 pins and QFN as far as I know offers only 75 pin packages. Is there any pasckage which is similar to QFN but has more number of pins. Also as the number of pins in the QFN package increases the package parasitics also increase. Please guide me further in this topic.
Thanks
Rittu
 

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