Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Diode varactor:How to increase capacitance vary range?

Status
Not open for further replies.
butterfish

butterfish

Full Member level 2
Full Member level 2
Joined
Oct 26, 2005
Messages
135
Helped
9
Reputation
18
Reaction score
3
Trophy points
1,298
Location
china
Activity points
2,012
Hi,
I need a diode varactor can integrate in IC, when add reverse bias voltage from 0~3v, the capacitance varies as large as possible.
For N+/Psub diode in standard CMOS process, when reverse bias voltage from 0~3v, capacitance vary only 2 times, how to get larger vary range?

Anyone has experience in CMOS process, could you share with me? Thanks a lot!
 

Is it practical for you to switch in a fixed capacitance when you have run out of range on your varactor?
 

Ratio (Cmax / Cmin) ~ 2 is standard in IC process, unless special varactor is provided.
 

    butterfish

    butterfish

    Points: 2
    Helpful Answer Positive Rating
psmon said:
Ratio (Cmax / Cmin) ~ 2 is standard in IC process, unless special varactor is provided.
Click to expand...

thanks for reply, could you explain more detail,
how about the process structure of the special varactor?
do you know which process fab have this special varactor IP?

thanks!
 

Take a PN junction (both MOS and diode varactor), the capacitance changes when the depletion region is increased or decreased. When you increase the region, the electric field across this region increases. There has to be a limit before this junction enters breakdown. So foundries set a conservative limit for reliability issues.

Infineon offers a special varactor for their SiGe BiCMOS process (they use an extra doping layer to increase the tuning range). I don't have their designkit and so i can't check.

Hope this helps!
 

    butterfish

    butterfish

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top