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The pros and cons of CMOS LNA by Razavi

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Puppet1

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CMOS LNA by Razavi

Hello

I am reading Behzad Razavi's paper on "CMOS RF Receiver Design for Wireless LAN Application" I think from 1999's IEEE CICC.

He has an cascode LNA in CMOS, degenerated with an inductor and has an LC tank. Above the tank he has a diode connected NMOS acting as a bias I assume (I am not sure please clarify).

In another earlier paper of his, in 1997 (Symposium on VLSI Circuits) he biased the LNA with a resistor conencted to a diode connected transistor and a current source at the gate.

What are the advantages and disadvantages of the two schemes ?

I have never seen a CMOS LNA biased with diode connected NMOS before.

Thanks
 

thcm

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CMOS LNA by Razavi

Hi,Puppet1,Can you upload the schematic first?
 

cetc1525

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CMOS LNA by Razavi

does it use for voltage level shifting
 

Puppet1

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Re: CMOS LNA by Razavi

here it the circuit

look at M3, what is it's purpose ?
 

nathan

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Re: CMOS LNA by Razavi

It provides with the correct common mode voltage to the mixer input.

nathan
 

Puppet1

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Re: CMOS LNA by Razavi

and what would that voltage be relative to VDD ?

And is it be using as a bias for the LNA too ?
 

ARTMehr

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CMOS LNA by Razavi

find more info :

h**p://www.ee.ucla.edu/faculty/bios/razavi.htm
 

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