why LC VCO has so big flicker noise upconversion?

My LC VCO is working at about 2GHz. Phase noise between 100khz to 1MHz offset has a -26dB slope. Even after 1MHz offset the slope is still bigger than 20dB/dec. Phase noise at 1MHz offset is -116dBc/Hz.

How to improve the flicker noise upconversion? It seems the flicker noise upconversion is the dominant phase noise source since most of the phase noise specs is defined below 1MHz offset say 100khz, 600khz and 1MHz.

Thanks.

check paper by hegazi and abidi

You can refer to Hegazi's book. They suggested to use LC filter to block the tail device's flicker noise.

thanks guys.

what confuse me is that flicker noise corner for 0.25um process is about 1MHz if minimum chanel length is used.

I am using 0.18um process for the VCO with minimum channel length. I expect the filcker noise upconversion will end at about 1MHz offset but it seems not.

You should simulate the device alone to get the data.