mazelk
Advanced Member level 4
VCO starting constrain
According with some reported VCO designs, active transconductance must overcome to tank transconductance, at least, in a factor of three (that they call "alpha" factor, or safety factor)
Why this amount?
I guess that it's not completelly true. As you increase "alpha", you increase transistor geometry (for same bias current) and drain capacitance (I mean about a complementary LC VCO). This reduce LC tank inyected current, and voltage swing. This increase phase noise.
Regarding those assumptions, which "safety factor " should I take to overcome tank loses?
Is it polite to consider that increasing "safety factor" could lead to drawback ??
According with some reported VCO designs, active transconductance must overcome to tank transconductance, at least, in a factor of three (that they call "alpha" factor, or safety factor)
Why this amount?
I guess that it's not completelly true. As you increase "alpha", you increase transistor geometry (for same bias current) and drain capacitance (I mean about a complementary LC VCO). This reduce LC tank inyected current, and voltage swing. This increase phase noise.
Regarding those assumptions, which "safety factor " should I take to overcome tank loses?
Is it polite to consider that increasing "safety factor" could lead to drawback ??