why my power conumpton extracted from direct plot-power is much smaller than Vdd*Idd?

Dear friends,

I simulated a simple RF circuit and do the pss and save all. As everything is all right except the power. Why the power plot displayed to me is much smaller than I estimated? Which one should I trust?

Enclosure is the plot and my circuit is specified by a supple voltage of 1.2V and a tail current source of 530u.

Vdd*Idd = 0.636mW = -1.97dBm
The Cadence tutorial indicates that the power plot's DC power is the power consumption, that is -6.56dBm = 0.22mW

Please help me as my report deadline is coming!

Thank you all for your time.

Justin

Hi, I am not sure if it has to do with your issue, but check this article: http://en.wikipedia.org/wiki/AC_power

Regards,
Nicolae