Absolute Maximum ratings of RF Devices

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Hi,

Can someone offer some insight please relating to absolute maximum ratings of RF devices? I outline an RF FET case study below:

Absolute maximum rating from datasheet
Vgsmax=-10 to +3V

Relevant Device RF Data @ operational Frequency
Zin=+17.8-j16.

Relevant Operational Details
RF power in=29dBm (794mW)
Quiescent Gate Voltage=-1V (DC bias)

Calculations
I did a fundamental “Ohm’s law” type calculation to determine what the RF voltage swing would be on the device input (Gate)
Vpp=2*sqrt(2*P*Zin), Vpp=12.3V so that the RF swing is between -7.2 and +5.2V. The analysis suggests that at the top of the RF swing, the device Vgsmax is exceeded, and this can therefore be seen as a potential failure scenario.
I have posed this question to colleagues, some of whom claim that the “Absolute Max rating” described is purely a DC parameter, and that that it did not apply to RF. Same colleagues however, could never provide theoretical validation of this assertion.
Can someone please validate the logic here or otherwise explain why the thinking is flawed and offer an alternative idea to relate absolute DC limits and operational RF extremes.

Thanks,
BK Parker
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2 Replies
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Hi BradP01,

Would you please let us know which Infineon RF product are you referring to? I cannot find any RF FET with abosolute maximum ratings as you mentioned.

Best regards
Luxun
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Hi Luxun,

I’ve been on leave, hence the delay in response. The truth is, the specific device I refer to above is NOT actually an Infineon product. I used Nitronex NPTB0004 as a case study. But the question is generic. I ask this question of myself for any power RF device I may use, but can never get any confirmation from peers that the logic is correct and I am not missing something fundamental.

Regards,
BK Parker
PS :I had hoped this to be a general engineering forum, but if it is limited to issues regarding Infineon devices, please accept my apology.
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