What is the difference b/w 1-stage or 2-stage LNA ??

[passerby]

LNA stages

For the RF font-end design, you can use 1-stage LNA or 2-stage LNA.

A. Filter --> LNA

B. Filter --> LNA --> Filter --> LNA


What's the advantage & disadvantage between A & B from technical point of view.
Such as NF, gain, interference surppression....

Any good document ??

Thanks.

 

[vfone]

Re: LNA stages

First option due to lower Gain have better intremodulation behavior.

Second option has higher Noise Figure, but higher Gain.

The most important contributor to the system NF is the first stage.

The Insertion Loss of the first filter it will add dB by dB to the total system NF.

Using two filters improves the out of band interference.

 

[passerby]

Re: LNA stages

Is there any article analyzing these two topologies?

Thanks.

 

[shogun]

Re: LNA stages

To find out more on this subject, you should look at the book called "Communications Receivers" by Rohde

Shogun

 

[bharat_gill]

Re: LNA stages

You can try to simulate the two circuits and see the advantages and disadvantages of each parameter important to your design...you can get simulators like ansoft, microwave office for trail if you dont have access to one...

 

[dingjingfeng]

LNA stages

A small area(simple structure, simple application etc)
B for better perfornmance Larger area(usually),