Sep 17, 2021 #1 G gkini19 Newbie level 5 Joined Jul 22, 2021 Messages 8 Helped 0 Reputation 0 Reaction score 0 Trophy points 1 Activity points 86 Hi All, I am using the circuit shown below. I want to have a tuning range of 2-4 GHz for LC VCO. I want to use the varactor in this configuration. My question: 1) How can I find the capacitance of the transistors used as a varactor? which analysis should I use and which plot will be useful? 2) To have a tuning range of 2 GHz how many stages of such Varactors should I have? is there a method or a way to choose this? Thanks all in advance
Hi All, I am using the circuit shown below. I want to have a tuning range of 2-4 GHz for LC VCO. I want to use the varactor in this configuration. My question: 1) How can I find the capacitance of the transistors used as a varactor? which analysis should I use and which plot will be useful? 2) To have a tuning range of 2 GHz how many stages of such Varactors should I have? is there a method or a way to choose this? Thanks all in advance
Sep 17, 2021 #2 D dick_freebird Advanced Member level 7 Joined Mar 4, 2008 Messages 8,984 Helped 2,333 Reputation 4,683 Reaction score 2,518 Trophy points 1,393 Location USA Activity points 71,562 I prefer to do it like a C-V probe pull would - ramp Vg{dbs} at fixed dV/dt and capture Igg. You've got I and dV/dt so you know C and can plot or fit vs V. Soon you will also care about Rgg but that's for someone more RF-y to chime in on. Upvote 0 Downvote
I prefer to do it like a C-V probe pull would - ramp Vg{dbs} at fixed dV/dt and capture Igg. You've got I and dV/dt so you know C and can plot or fit vs V. Soon you will also care about Rgg but that's for someone more RF-y to chime in on.