THe LNA design ? inductor Q and current ?

[mitgrace]

inductor q

Dear All :

Does anyone have know the inductor Q with current relation? I read some paper. it decribe the high Q , the current cab reduce ? And I ahve see the figure about Q and cuurent ? Does anyone know how to do this design ? Simulation and any formula ? thanks

 

[xxargs]

Dear All :

Does anyone have know the inductor Q with current relation? I read some paper. it decribe the high Q , the current cab reduce ? And I ahve see the figure about Q and cuurent ? Does anyone know how to do this design ? Simulation and any formula ? thanks

Mostly case no relation in case of free air-winded inductor, exept for heating in winding itself (give higher resistance on heat) in case of high current, but if you using ferrite core and other magnetic lossy material, you have current relation to used core material (magnetic saturation etc.).

 

[Yakeen]

Hi,

You must read about Skin Effect in order to understand relation between I current and Q factor

 

[khouly]

for simulation and design of spiral inductors , check ASITIC , it is very simple , and then u will have to simulate ur Spiral with EM simulator like Momentum , IE3d or even HFSS , to get all the parasitics and effects

for a very simple equation , reffere to the razavi book "ic's for optical communication the LC oscillator chapter"
and clavin pelet book "RF integreated circuit design" the chapter of passives

and check for IEEE papers about modeling of spiral inductor

khouly

 

[xxargs]

Hi,

You must read about Skin Effect in order to understand relation between I current and Q factor

Hmm...

Skin effect vs. frequency for resulting resistance and Q-value for specific frequency - yes, but not depend of used current for used frequeny - you make passive intermodulation if you have nonlinear relation between current strength and resistance. And in most case, air winded inductance is not know for this unlinear effect even in very high power using situation...


Passive GSM equipment have demand to make minimum 174 dBc [1] passive IM product on 2x20 Watt carrier test case and is not possible to make if equipments inductance have sligthest unlinear relation between current and resistance in structure.


[1] Ie. 2 x +43 dBm carriers never make more IM-products higher than -131 dBm signal strength...

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Well know current depend resistance is a diode, and make huge IM in multi carrier situation... ;-) ...or rusty nail in roof of aluminium plate and near multiple high power carrier from RF-trancivers and resulting interferenced or/and blocked other recivers... (co-site problem) :-(