2560 MHz 2670 MHz LNA using NE3510M04
i am a final year student working on 2560 - 2670 MHz (S-Band) LNA using HFET NE3510M04 (Vds = 2 V, Id = 15 mA) as my final year project. this transistor is potentially unstable in wideband frequencies
my guide lecturer suggests that i use resistive loading and inductive degeneration method to improve the rollet factor so that it will be above 1 IN ALL FREQUENCIES.
my problem is i can't get good values of resistance to achieve it. after trial and error i found that only high value of resistance will achieve it but this will get me a low gain and relatively high value of noise figure. In short, i'm still dying to get a good stability in this transistor
so i want to asking help from you guys to solve this or maybe you can point out the mistakes in my design so far (i'm using ansoft serenade SV 8.5). i attached the design, datasheet, and the s-parameter if it's help.
sorry for the bad english
yours sincerely
try to reduce the inductive degeneration values to 0.1 nH per inductance and instead of resistive loading (which rf cracks always dismiss...have a read on it "Microwave Transistor Amplifiers Analysis and Design" by gonzales) try a parallel branch (which will do the same trick without affecting nf too much) with a 15pf condensator for decoupling and a 20 ohm resistance...stabilizes the thing from 0.5 ghz - at least 10 ghz and keeps nf < 1.8
Try to use resistive feedback and it will do the job if your noise figure required specification is too low. Dont forget to put capacitors on the feedback network to isolate the output from input. You may try this link: Ongoing Projects
This technique is explained in the first work on the page.
Best regards,
Canosa
Why don't you use feedback ? A parallel feedback will improve your stability factor.If you also optimize this feedback for your frequency band which you're interested in, it gives you the gain that you look for..