RF output power vs. Frequency 1

• Dec 22, 2003

1
• #2

TWW

Electrical

Jun 10, 2003

50

US

Pmax is typically proportional to the inverse of 1/freq, or 1/freq^2 depending on the device. Threrefor you could expect 25-50W of optimized power.

 

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• Dec 22, 2003

• #3

TWW

Electrical

Jun 10, 2003

50

US

BTW. 1/f is electronically limited, 1/f^2 is thermally limited.

 

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• Dec 22, 2003

• Thread starter
• #4

zjxie

Electrical

Dec 22, 2003

2

US

Thanks TWW,
What's the physics behind the electrical limitation and thermal limitation?
Does it due to the lower output impedance in higher frequency? Why the thermal become worse in higher frequency? Is the drain efficiency worse?

 

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• Dec 22, 2003

• #5

TWW

Electrical

Jun 10, 2003

50

US

My humble attempt to answer these deep questions.

Question 1:

Electrical Limitation: Fundemental material parameters effects such as saturated drift velocity, mobility, gate length or base thickness, various resistive and reactive parasitic elements.

Thermal Limitation: Junction temperature rise, device area, thermal resistance.

Question 2: The lower impedance is part of the problem, the other part of the nasty equation is the rising reactance.

Question 3: Large Signal Drain efficiency will most likely be worse, whereas the small signal value may not change much.

Gota Go

 

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