sheldon
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Hang,
1) A 0.25nH inductor at 5.6GHz is equivalent to a ~9Ohm resistor. Unless you are biasing the amplifier at very high currents, the signal swing across the degeneration inductor will not be very large. Guess high is relative.
2) Yes, the gain node can swing outside the power supply. This may be a good thing for RF designers because you can increase the signal swing without increasing the power supply. However, you need to make sure that the reliability ground rules for process are not violated. This effect is common, for example, ground bounce of digital circuits.
Best Regards,
Sheldon
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