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Dear Vfone, Bigboss,
I appreciate your time and kind advice.
About radial stub: there are some IEEE papers use radial stub for PA at S band like showing in the attachment as an example.
In the datasheet of TGF2977SM it says this device can work from DC to 12 GHz. However, in the datasheet of...
Thank you.
My targer operation frequency is 2.4GHz. I just would like to say that they don't use a radial stub for application circuit at 9GHz-10GHz is because it is difficult to find an available bypass capacitor which has a self resonant freq at this freq range.
I wonder if my issue is the...
In fact, I didn't design follow the application circuits in the datasheet. I made my own design based on my knowledge, indeed.
I think that they don't use a radial stub at 2.6-4.2GHz is due to its large size. In addition, at X band, it is relatively difficult to find an SMD commercial bypass...
-You can send me ADS project file with embedded Modelithics model to review in detail..
Many thanks, please find the link for my zipped ADS project: **broken link removed**
Actually, I don't have much experiences in designing PA using QFN package devices like TGF2977 of Qorvo. I checked...
Thanks, but as you can see the small-signal results look quite good. In fact, I already tried to connect a bypass capacitor at the point of radial stub but the results didn't get better. I doubt that the main cause is, as indicated by BigBoss, the accuracy of the large-signal model of the...
I measured Id with a current probe in the drain bias line in simulation.
Pin was measured with a power calibration using power meter not just reading from the the SG.
This PA has actually a poor design of S11, this is not usual in PA design where S11 should be good while S22 should be poor...
I agree that the large-signal model of transistor may be less accurate. However, the small signal model looks good as shown in the attached figure.
What do you think about there any any other critical causes of this issue?
Hi,
Could anyone tell me what is the cause of the significant difference in drain current between simulation and measuremet of a PA which I just designed. Does this difference mean a difference in output power between Sim. and Meas.?
Pls check the attached figure. Solid line is Sim. and dotted...
Hi all,
Thanks a lot for your time and kind considerations of my issue.
Attachment is the backside of my PCB. I used a buffer thin aluminum plate to make ground connection for SMA connector since the substrate height is just 0.75 mm.
The square cutout in the aluminum plate is at the...
But what is also required is careful connection, you have introduced so much parasitic inductance in your coax-to-PCB transition that I would not trust your measurements. Looking at your photo, that is a several nH parasitic series L due to the gap and the long ground path.
What does the...
Thank you. Do you mean I should try a combination of a RF-bypass capacitor with a RF-choke inductor using SMD components?
Anyway, I will try bias methods in the literature you posted to check if the issue caused by bias circuit.
I forgot to mention one more important thing, when I made a...
I understood that 50 Ohm will not change no matter 50 Ohm line length added. However, do you think that the transition is not an uniform lines with 50 Ohm?
As you can see in my measurement of the output matching circuit, when I used port-extension technique in VNA to compensate the phase shift...
Thanks for your kind suggestions.
I will post backside of my PCB later. Actually, since the substrate height is just 0.75 mm, I used a buffer aluminum plate on the backside for soldering the SMA ground edge mount to ground PCB.
The transistor should cause the deviation but I don't know how to...
Thanks for additional information.
In my situation, deviation in magnitude between EM Sim. and Meas. is not so significant at low frequencies including 2.4 GHz as attached pictures.
It becomes large at high frequencies as you indicated.
However, as you can see in my attached pictures, phase of...
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