How to design broadband LNA for (0.5 -3)GHz?
Please tell me from where i have to start my project
The library.
Dear 246,
First choose suitable transistor, which has less Noise Figure and maximum gain, later design input and output matching circuit. Once design matching ckt, check the stability , if ckt is unstable , make it stable.
Google will give you more than enough info.
Your project is to help you understand what it takes to create something
form nothing.
Ask yourself what do you need, then go look for it. Having others
tell you what to do is harmful to your development as an Engineer.
Do you want to design a LNA as a MMIC? Or do you want to design it as a module? What's your target specifications, such as Gain, NF, etc.?
maybe consider resistive feedback to get flat response over the wide bandwith.
Some tips for your LNA..
-Your LNA will potentially have feedback circuit in order to achieve this bandwidth.
-Your LNA will probably be Cascode configuration due to very wide bandwidth.
-You should use SiGe or pHEMT device at those frequencies to provide Low Noise but it's not necessary recent Bipolar devices are also good-Look at www.avagotech.com
-You must consider and take the priority Noise Figure,Gain,IIP3,IRL,ORL respectively.
Dear 246,
You can use AVAGO company transistor ATF34143_3V_20mA, ATF54143_3V_80mA for obtain low noise figure and maximum gain.
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Dear 246,
You can use AVAGO company transistor pHEMT ATF34143_3V_20mA, ATF54143_3V_80mA for obtain low noise figure and maximum gain.
for such broad band and to save the hassle of the discrete design, I d think about below devices, which have quite flat response.
http://www.avagotech.com/pages/en/rf...plifiers/2103/
http://www.avagotech.com/pages/en/rf...plifiers/2303/
however, package is really small, not everybody is OK with this.
br
dear bigboss
could you recommend some books about the Cascode configuration and feedback circuit ? I want to understand the fundamental about it.
thank you very much!