Hi SCV
Trying to understand your ckt better:
It seems like you first tried a varactor, and also tried flipping its polarity and noticed Phase Noise degradation?
You then also tried some MOSFET as you mention drain/source terminals?
You could post an image of your portion of the circuit to avoid any confusion. You may download IrfanView to capture image and save it as JPEG and then attach that here.
I look forward to hearing in regard to this. Phase Noise issues interest me a lot.