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Design >> RF Design >> flicker noise of the down mixer
https://designers-guide.org/forum/YaBB.pl?num=1162208284

Message started by sivacha on Oct 30^th, 2006, 3:38am

Title: flicker noise of the down mixer
Post by sivacha on Oct 30^th, 2006, 3:38am

hi
while designing the down mixer(active, folded mixer), iam facing a serious and well known difficulty with the flicker noise of the input switches.
Gain, noise figure and linearity are conflicting with each other.
Gain increases----> noise figure improved ------> linearity is lost.
Could you please suggest the good optimization for these??
Receiver:: Low IF type
Freq range of operation:: 2.4GHz

thank you...

Title: Re: flicker noise of the down mixer
Post by aaron_do on Oct 30^th, 2006, 8:45pm

How low is your IF? If it is above 1 MHz you should be able to avoid the flicker noise problem. Gain NF and Linearity always conflict. I suggest you optimize based on your receiver requirements (i.e. for what purpose?). You will need some idea of all the other stages performance also (channel select filter, VGA etc)

Aaron

Title: Re: flicker noise of the down mixer
Post by sivacha on Oct 30^th, 2006, 9:48pm

aaron_do,
my IF is 1MHz.
this receiver is for BT2.0 Enhanced Data Rates.
my main concern is the flicker noise of the LO switches.

Title: Re: flicker noise of the down mixer
Post by aaron_do on Oct 31^st, 2006, 4:50am

I don't really know anything about your system of the bluetooth 2.0 specs. I asked a question previously about system NF calculation and found this paper very helpful. Its posted in the link:

http://www.designers-guide.org/Forum/YaBB.pl?num=1157358393

based on your system specs you can estimate the required gain, NF and linearity.

hope it helps,
Aaron