I am designing a cross coupled VCO using CMOS technology. Now I got some question of the tuning frequency.
The frequency is always much higher than I expected. It can not achieve the lowest frequency which the varactor is supposed to. What is the reason of this problem? Can I measure the capacitance of the varactor? I am using Cadence spectreRF.
I am designing a cross coupled VCO using CMOS technology. Now I got some question of the tuning frequency.
The frequency is always much higher than I expected. It can not achieve the lowest frequency which the varactor is supposed to. What is the reason of this problem? Can I measure the capacitance of the varactor? I am using Cadence spectreRF.
this is the right equation ,
C is the varactor capacitance + parasitic capacitances
L is the inductance of the coil.
then u have an error in one term of these
another thing , u may have an error in SpectreRF setups. did u follow the manuals and appnotes given by cadence