Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic 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.

[SOLVED] Is there a method on circuit level to adjust the threshold voltage of a MOS?

Status
Not open for further replies.

Lt_Garillios

Newbie level 5
Joined
Apr 21, 2011
Messages
10
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,336
As the title says :)

I need to adjust the threshold voltage of a transistor and was wondering if there are any concrete methods for doing that at circuit level? Or do I physically need to adjust the gate?

Cheers,
 

allsey87

Member level 4
Joined
Sep 27, 2010
Messages
70
Helped
17
Reputation
34
Reaction score
17
Trophy points
1,288
Activity points
1,902
The threshold is generally fixed and defined at the difference between the source and gate voltages, depending on what you are trying to achieve (what the configuration of your circuit is) potentially using diodes to clamp voltages can be of some use...
 

saiaditya

Junior Member level 2
Joined
Sep 23, 2009
Messages
21
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,391
If you want to increase the threshold voltage, then you can use body effect (source biased at higher potential than bulk) and also larger lengths and also vt varies with vds...but the minimum vt will be set by the process and i dont think you can go lower than that in the circuit level. So if you require lower vt's then you need to look at the fabrication process
 

aindejeje

Junior Member level 2
Joined
Sep 29, 2009
Messages
21
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
1,416
yes by using bulk biasing.
you can make it higher or lower depend on polarity of the bulk voltage.
 

saiaditya

Junior Member level 2
Joined
Sep 23, 2009
Messages
21
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,391
I dont think you can forward bias the bulk-source junction (NMOS). So the bulk always should be at a lower potential and with higher source voltages your vth increases
 

Lt_Garillios

Newbie level 5
Joined
Apr 21, 2011
Messages
10
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,336
Thanks a lot guys! Adjusting the bulk did indeed solve my problem :)
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top