How to design an ultra-low noise LNA?

[tungchang]

Ultra-low noise LNA?

Could you give me some advices about designing ultra-low noise LNA? The range of the frequency is 1-3GHz and the NF is under 0.5 in room temperature. what's the better transistor for these targets? I try to use feedback model but oscilliation can't avoid. my transistors are NE321000 and Ne710.

 

[eladg]

Re: Ultra-low noise LNA?

Could you give me some advices about designing ultra-low noise LNA? The range of the frequency is 1-3GHz and the NF is under 0.5 in room temperature. what's the better transistor for these targets? I try to use feedback model but oscilliation can't avoid. my transistors are NE321000 and Ne710.

i did it. i didnt have oscilliation.
1) what is the freq that u get osc? (if it is abouve 5 giga, try to put ser-coil

 

[mozee]

Re: Ultra-low noise LNA?

describe your board layout. if you have to much inductance in your ground leads I.e. source lead for NE710 it will oscillate. Try and have a via or two to ground directly underneath the package lead to be grounded and have the PC board 0.062 or less as a start.

 

[mozee]

Re: Ultra-low noise LNA?

describe your board layout. if you have to much inductance in your ground leads I.e. source lead for NE710 it will oscillate. Try and have a via or two to ground directly underneath the package lead to be grounded and have the PC board 0.062 or less as a start.