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

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Lt_Garillios

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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,
 

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...
 

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
 

yes by using bulk biasing.
you can make it higher or lower depend on polarity of the bulk voltage.
 
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
 

Thanks a lot guys! Adjusting the bulk did indeed solve my problem :)
 

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