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Simulators >> RF Simulators >> ADS Questions - about NFmin for AT41486 transistor
https://designers-guide.org/forum/YaBB.pl?num=1212376329

Message started by mrnobody on Jun 1^st, 2008, 8:11pm

Title: ADS Questions - about NFmin for AT41486 transistor
Post by mrnobody on Jun 1^st, 2008, 8:11pm

Hi,
I was wondering if I can get some advice here..
I am trying to design an LNA using AT41486 in ADS.
According to AT41486's datasheet, the NFo at 2GHz is 1.7dB at 2GHz, VCE = 8V and IC = 10mA.
However, in my ADS simulation (which the transistor is biased to Vce of 8V and IC of 10mA), the NFmin is around 23.
Attached is both the S param layout and the result.
I am not sure what I have done wrong..
Please advice.. thanks..

Title: Re: ADS Questions - about NFmin for AT41486 transi
Post by pancho_hideboo on Jun 1^st, 2008, 9:29pm

I can't find any design issue in your post.
Your question is not design issue but simple usage of EDA tool.
Please post to
"The Designer's Guide Community Forum ≫ Simulators ≫ RF Simulators".
Or
Agilent Home >Products & Services > Test & Measurement >
Agilent EEsof EDA > EEsof Knowledge Center > Discussion Forums
Agilent EEsof Forums > ADS > Analog Simulation
https://edasupportweb.soco.agilent.com/cgi-bin/yabb/YaBB.pl

This is packaged BJT model.
AT41486 have 4 pins(c, b, e, e).
You open one emitter pin.
Try connect two emitter pins.

And why don't you set C1 as 10pF//100pF.

I've found your mistake.
You've set wrong port number.
You shouls set num=1 for input port.
And set num=2 for output port.

Title: Re: ADS Questions - about NFmin for AT41486 transi
Post by mrnobody on Jun 3^rd, 2008, 5:35pm

Thanks for the reply..
The NFmin obtained is 2.706dB, shouldn't it be 1.7dB (NFopt in datasheet)? I mean, shouldn't the NFmin's value be equal to NFopt value shown in datasheet..?
If I understand correctly, MFmin is the minimum Noise Figure of that transistor at VCE = 8V, IC = 10mA and Freq = 2GHz. Is it possible to make the NFmin lower, maybe around 1.7dB..? Please advice. I am very new in ADS thanks..

Title: Re:
Post by pancho_hideboo on Jun 21^st, 2008, 10:00am

You are using old version of AT41486("pb_hp_AT41486_19920721"). Maybe this old version is not proper since it gives 2.55dB as NFmin even though I invoke ideal measurement condition.
I don't know why Agilent keeps to bandle this old version. You should contact with Agilent EDA support.

As GummelPoon Model, there are following three versions.
#uselib "RfTransistorLibrary" , "pb_hp_AT41486_19920721"
#uselib "RfTransistorLibrary" , "pb_hp_AT41486_19921101"
#uselib "RfTransistorLibrary" , "pb_hp_AT41486_19931202"

As S-parameter models, there are following two models.
"sp_hp_AT-41486_1_19920721"
"sp_hp_AT-41486_1_19921201"

If you use S-parameter models, you get completely 1.7dB as NFmin.

And if you use "pb_hp_AT41486_19921101" or "pb_hp_AT41486_19931202", you get almost 1.7dB as NFmin.