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LNA stability problem at low frequencies (Read 3212 times)
skywlj
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LNA stability problem at low frequencies
Apr 14th, 2008, 6:43pm
 
I'm designing a LNA at 2.4GHz but finally the low frequency stability becomes a problem. Any good solution for that? If resistors are added to stabilize the circuit, the noise figure and power gain will be much worse.
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aaron_do
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Re: LNA stability problem at low frequencies
Reply #1 - Apr 14th, 2008, 11:21pm
 
Hi,

i don't think you gave enough details. Perhaps a schematic would be helpful, or at least a description of the circuit...

Aaron
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skywlj
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Re: LNA stability problem at low frequencies
Reply #2 - Apr 15th, 2008, 2:16pm
 
The source inductor degenerated LNA with cascoded structure is used. The output for Kf and Bf at low frequency is very large 10^66 at very low frequency. The Kf and Bf from 100 KHz to 200 KHz is attached. It looks very funny. For higher frequency ( from 1MHz to 10GHz), the reported Kf and Bf are normal and show the LNA is stable. Does this come from the computing error?
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Kf_Bf_100k_200k.jpg
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