Hi TimFox,
Thanks.
As I understand it, you are talking about the negative half cycle of the RF current which must not be able to discharge the charge buildup in the intrinsic layer?
According to literature:
Q >> I_RF/(2*pi*f) : I_RF = assuming RMS current (not peak). f = operating frequency = 1000 MHz.
where Q = I_f * tau : I_f = DC forward bias current. tau = carrier lifetime.
Assume I_f = 10 mA and tau = 100 ns. Q = 1000 * 10-3 * 10-9 Coulomb = 1 nC.
Assume the RF current being a sine wave with amplitude 200 mA. During the negative half cycle, the RMS current is 200 mA/sqrt(2) = 142 mA.
Hence: 142 mA /(2*pi*1000 MHz) = 0.0226 * 10-9 C Coulomb = 0.0226 nC << Q = 1 nC
Still, if the datasheet specifies a maximum current for the PIN diode of e.g 100 mA, will the example above hold?
The DC current is 10 mA, but the peak conducting current across the PIN diode during the positive half cycle is 200 mA + DC bias current (and most likely 200 mA - DC current in the other half cycle)!