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We have used a 50 ohm resistor in the gate, a parallel combination of 50 ohm and 3.5 pf for stability at the input. We have used 100nF and 3.5pF as RF bypass capacitors.
1717097537
Could you please tell me what these circles imply in the demonstration circuit?
Thank you so much. I will do better in my next design. Is there no way to save this one though? Or test it somehow? We could not see any oscillations in the SA.
Yes, we did not use them. I do wish to understand though. We have seen many papers that implement bias networks of their own, i.e. not following the demonstration schematic.
Is it then absolutely necessary to follow the schematic?
T
Thank you so much for your input. We are new at this and since we have no clear guidelines, we are making mistakes. We will definitely look into the ground plane. Is this the reason our DC is not stable?
1716926459
I would really appreciate if anyone can share a good and reliable source...
We checked and the S21 was less than -10dB from 1-3GHz and below -30dB in the rest. We tried to check for oscillations by limiting the current and saw no spike in the SA. We then gave a 25dBm input signal to check if we get any power at our desired frequency (1.8 GHz, 2.4 GHz and 3.5 GHz) and we...
Hello,
We designed a class AB PA using CG2H40010F (VGS=-2.4V, ID=250mA) on Rogers 5880 (Er=2.2). We did the S-parameters measurement and they were in good agreement with the simulation. We did notice post measurement that our board was slightly warmer (we did use a heat sink of 40x60mm...
Yes, we did the EM simulation using ADS Momentum. We did not take the coupling of the DC wires into consideration. Also, the screws are used for the heat sink placed below.
Thank you for the suggestion. I will definitely look into this.
1714331709
We are unable to properly bias our transistor. Could you suggest how do we go about testing it for oscillations then?
There was no jump in drain current, just the gate. I understand that we needed the bypass capacitors. Our circuit is stable. We did the EM simulation and k>1 from 30 MHz to 15 GHz.
Why would you put it like that?
We have only recently started working on active circuits in our lab. We do not have the best available facilities for soldering components. We found a couple of papers in which the bias network was designed without the bypass capacitors and figured this was a...
I understand that but we only tested for DC. We didnt give any RF signal.
1714175526
Yes, we did.
1714175744
We performed the DC test first. We wanted to check if we get the right drain current. We did not give the RF signal.
We designed a bias network for Cree CG2H40010F for a triple band power amplifier on Rogers substrate (Er=2.2, h=0.787mm). We biased the transistor with the typical values of Vg=-2.6V and Vd=28V. On doing so, we observed a current of 150 mA in the gate and voltage drop in drain the moment we...
This is the circuit. I used SRFT to design the matching network. Load pull simulation was done for each frequency to obtain the load and was around 24+3j ohms in the band.
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