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Broad band dsign of LNA best topology

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narayani

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I want to design LNA from 12-18 GHz. I want to get s11 and s22 less than -10 dB. Which are the best topologies for obtaining broad band LNA from 12-18 GHz. Can you guide to obtain S11 and S22 less than -10 dB from 12 to 18 GHz.
 

Any other configuration for broad band matching will advice
 

Check tunable matching networks.
Do you need all 12-18 GHz band, or there are some particular frequency bands?
 
Distributed Microwave Amplifiers are also very popular for wide-band applications.
 

I want to design LNA from 12-18 GHz, and am using following circuit with source degenerated inductor. Once I follow this circuit and keep changing one or other components values ( Input matching C and L or Source degenerated inductance L or gate inductance L). For example, once I change feed back capacitance or source inductor or gate inductor or matching capacitor or inductor values. I am loosing one or two important parameters of LNA. Sometimes I loose Stability or input (S11) or output return(S22) losses or gain(S21) of LNA or NF.
I am not getting all the desirable parameters (S11, S21,S22,S12, noise figure, stability) at a time. What should I do, can you advice
 

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Try to eliminate resistors at the input stage. But you can use some resistor network at the output to match broadband. You will lose some gain but it is easy. It also provides improved stability.

- - - Updated - - -

BigBoss said:
Distributed Microwave Amplifiers are also very popular for wide-band applications.
Click to expand...

I think it is not needed a distributed microwave amplifier for 12-18 GHzband. You need several transistors and and complex matching networks.
 

You can use two cascaded stages for wide-band design

1) cascode CS or CG amplifier (with CG you will have better input matching)
2) single transistor common source

If you have two drain inductors, by tuning them and decreasing their Q you can get 2 different peaks which will increase your bandwidth.

You can design an wideband input matching using ADS with lumped components (output as well)
 
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