Moscap in loop filter

[majormac]

Has anyone used moscap in a PLL loop filter? High capcitance per unit area is attractive. But I am worried about gate leakage current.

 

[sunking]

dont worry about it.
the leakage is very small.

 

[rfsystem]

Make shure that the cap variation over voltage does lead to PLL instability!

 

[flushrat]

If <=.13um process, be aware of leakage current. Use high-vt device or varactor or metal cap.
If .18u or above, no problem.

 

[majormac]

i thought that hvt or lvt devices have the same oxide thickness, which means same gate leakage. 2V devices would be less leaky comparing to 1V devices which have thinner oxide...