which application for CMOS LNA?

[jigisha]

hello all..
i m working on CMOS Low noise amplifier for my dissertation work...but i m confused for what application i should implement LNA?
i found some of the application on IEEE Explore..viz
1. OFDM
2. GPS
3. wi-fi/wi-max
4. ku band satellite services.
5. for wide band applications.
etc etc..
now i confuse for what application i should go for?
can any one guide me please???
thank you.....

 

[m100191ec]

All the applications which you have listed are related to the wireless transmission of signals. The aim of the LNA is to improve the noise figure of the system as it the first block in receivers architecture. Each application has got its own noise figure, gain,IIP3 etc. Based on the work(NF,S-Parameters,IIP3) you have done, see which application suits your work.

 

[jigisha]

your suggestion is right...
but i have to work on RF..i mean application working around 1GHz.
my work will be for any application whichever i select, for that have to achieve high gain with min possible noise NF...

 

[m100191ec]

what are the specifications for your circuit? I mean noise figure, S-parameters etc.

 

[tony_lth]

At 1GHz, the NF can be as low as 0.7dB or less.
gain normally should be greater than 25dB.

 

[jigisha]

actually i m working for my ME dissertation work...so at present i havent decided any applications...once the application is decided then i will go for specifications.....but i would like to work on differential topology of LNA. and would like to reduce power with minimum possible NF. and compare it with other topology like common gate,common source or cascode configuration....
yet i thought this to do...but i have not finalize the narrow area for dissertation work...

by d way....thank you all for taking good interest in my post....thank you so much...

 

[m100191ec]

In general for differential LNA, NF could be as low as below 2dB. But this value is a trade off between gain and power consumption. First, decide your frequency of interest upon which your circuit is going to act. For example, if you go for wide band applications, it is difficult to match the input and output impedance of the circuit to 50 ohms. The gain will roll off at high frequencies for which you have to compensate with the other techniques. Mentioned above are only few issues. Therefore, first decide your frequency of interest, then you can see what applications will fall under those frequencies.

 

[totowo]

Microelectronics is a kind of engineering.....What the application is should depend on those who pay you, such as your supervisor or your sponser.
Just like a company, what their products are should depend on the market and the consumer. even you have foresights on what they need.

Please don't design a LNA just because you 'wanna' do so. The application or purpose is the precondition of why a study makes sense.

Whatever, in my opinion, there are a lot of tradeoff performance in RF Frontend, NF/Gain/linearity/power consumption etc.
If you don't want to care much about linearity, the GPS LNA seems to be simplest.
Because the wifi/wi-max adopts OFDM modulation, so rather than NF, linearity is also important in each blocks of RF Frontend, means, a very good system assignment is needed(between LNA/Mixer/Filter....)
Above 5G, such as 60G(very popular now) and Ku band is challenging in CMOS process, and you should consider whether the test could be handled before you tape out...

I hope the above helps. But you really should turn to your supervisor first.

 

[jigisha]

thank you so much for your help......your post really helped me to narrow my dissertation area.....as i was basically a communication student so not clear much in field of vlsi communication....thank a lot....