Faizan shafi
Newbie level 5
My Schematic . Frist Image
I tried to make it a readable as good as possible for you. This is my circuit at the moment.
Red part is my DC biaising network. lnductors are my DC Feed inductors. There value os 200pH.
The transistor is x6. 7mA current is flowing.
Other than the matching networks. I have attached a resistor which makes my circuit stable at lower frequencies. Otherwise it is unstable at lower frequencies. The resistor value is 22ohms.
Blue one are DC Decoupling capacitors and their values are 40fF.
Seccond Image . DC Biasing Point.
It is point that i choose for my DC biaisng point
Third Image. S parameter Analysis circuit
If you look at the results . main circuit is barely stable at lower frequencies. It was only possible when i added a resistor at the base of my transistor . But my gain is now only 3dB. Ciruit is matched at the input and output side if you look at the conj (S11) and S22.
I am optimizing this circuit at 105Ghz.
Can you guys give me any suggestion as to how to increase the gain without making it unstable. I know some feedback circuit can help me but can you give me some tips about to to give a feed and what should i keep in mind while doing that.
When choosing the current density. I change the transistor multiplier and plotted the graphs pf NF and gain. I choose a point where I thought both were good enough.
Do you see any flaws in my approach.
I tried to make it a readable as good as possible for you. This is my circuit at the moment.
Red part is my DC biaising network. lnductors are my DC Feed inductors. There value os 200pH.
The transistor is x6. 7mA current is flowing.
Other than the matching networks. I have attached a resistor which makes my circuit stable at lower frequencies. Otherwise it is unstable at lower frequencies. The resistor value is 22ohms.
Blue one are DC Decoupling capacitors and their values are 40fF.
Seccond Image . DC Biasing Point.
It is point that i choose for my DC biaisng point
Third Image. S parameter Analysis circuit
If you look at the results . main circuit is barely stable at lower frequencies. It was only possible when i added a resistor at the base of my transistor . But my gain is now only 3dB. Ciruit is matched at the input and output side if you look at the conj (S11) and S22.
I am optimizing this circuit at 105Ghz.
Can you guys give me any suggestion as to how to increase the gain without making it unstable. I know some feedback circuit can help me but can you give me some tips about to to give a feed and what should i keep in mind while doing that.
When choosing the current density. I change the transistor multiplier and plotted the graphs pf NF and gain. I choose a point where I thought both were good enough.
Do you see any flaws in my approach.
