Tunable Integrated Capacitors (STPTIC) instead of Varactors in VCO's

[kurtulmehtap]

Hi,
Has anybody tried to use Tunable Integrated Capacitors (STPTIC) from ST in a VCO to replace varactor diodes?
I could'nt find a single reference on this topic.
Thanks

 

[kurtulmehtap]

I understand nobody worked on Tunable Integrated Capacitors for VCO's. What I don't know is if they are suitable or not.

 

[biff44]

they would work fine on a vco, since it is a single frequency, and I do not need to modulate the tuning element fast
.

these things are typically used for antenna tuning or tunable filtering, and their intermod generation can be a problem

 

[E Kafeman]

I have been using a product that seems to be very similar as STPTIC from https://www.psemi.com, for active antenna tuning. They call it DuNE.
Main disadvantage I can find is that DuNE have very limited tuning range compared to most varactors.
When I used them was they analog controlled. All current products from psemi seem to require a digital interface.
Have a weak memory that the company once was split and someone else did keep the analog portfolio.
As I have got it explained is it much same function as if a high DC voltage is biased on a plate capacitor.
The voltage makes the plates move toward each other and RF capacitance increases.
As it is a slow mechanical function will not a high frequency voltage cause any further modulation.
It was invented by accident when a regular ceramic cap was measured and it values changed when a high DC voltage was applied.
So have I been told :wink:

I have since long planned to check if a regular, say 0402 4.7pF NP0, how much it can be tuned within 0-10 Volt DC and stability over time.
It can be a nice knowledge as even a very small adjustment can be used for increased long term stability in narrow filters or generators.
It is possible that someone already have done similar experiments, and published the result, but I have not found any paper.