tiger_ads said:yes, i need match the lna to 50 ohms. i have swept the L and C values simultaneously, and in smith chart it can be matched in centre, but when i sweep frequence, the result is not correct. i think it may be oscillated, i want to know how to simulate the stability?? how can i improve it?? add a capacitor between gate and drain??
thanks
Added after 4 minutes:
i simulate this LNA using cadence SpectreRF, could you explain in detail??
tiger_ads said:to dsjomo
why do you speak so?? adding a cap between gate and drain is unvailable?? i have read a paper who suggest it, could you explain it?
i have read "Kf" , it<1, and Zout is negative,so this is not unconditional stable , how can i improve it?? add a resister at the output??
thanks!!
tiger_ads said:but how the resistor is connected? shunt or series?? what value? is there a rule which can be followed?? thanks
i try to add it ,one terminal is connected to cap which is used for matching,another is connected to 50ohms output, is it correct?
tiger_ads said:hi djsomo
i have simulated the circuit, the shematic(have added the resistor at the output) and simulating results have been attached. could you examine them, then suggest me to ajust parameter. thanks!!
are these curves correct??
the IIP3=-13.4285dBm, how can i improve it??
when plot the 1-dB compression poin and IIP3, setting the extrapolation point differently ,the result is different. how should i set this parameter??
i am a beginner in RF, having a lot of experience need to learn, sincerely hoping you can criticize me, i would try my best to improve myself! thanks again
tiger_ads said:i have done it followed by your suggestion, cout is connected to the common node of rout and lout, "Kf" is always more than unity.
now, could you explain how to consider parasitical facts? give me a direction! thanks!!
tiger_ads said:first of all, i should draw the layout, then extract the parasities including R ,C,
pad, and bondwire parasities?? i heard of Cadence can run package simulation,but i haven't used it!
the bias current of 1st stage is 6mA, the 2nd stage is used to improve the Gain,i don't care about it ,so i must check it first ,then tell you
thanks
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