FETs

Sep 17, 2009 4 Replies

Hi,



I am using the following FETs in a project


  1. FDS 9945
  2. NDS 9948

But their minimum threshold gate voltages are -1 and -1.5 volts. Does someone know parts that with similar properties but with much low gate voltages like 0.4 or 0.5 volts. Samller the better.



Thanks John


Ah, not really. You're pushing the state-of-the-art, AFAIK.

Germanium bipolar transistors turn on around 0.2V (with suitable base- current limiting resistor).

"john"

** You won't find any.

The gate threshold is deliberately set at those voltage levels so that any device supplied will *definitely* be non conducting whenever the gate is zero volts compared to the source.

This is a direct result of the tempco of gate threshold voltage for mosfets being 4 to 6 mV per deg C and the max operating chip temp being 175C.

In any case, both devices you quote are speced to be "on" for gate voltages of 4 volts and above.

..... Phil

You can't get mosfets like that. Maybe you should rethink your project and just jfets instead, or bjt's.

You might want to contact this company and ask:

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Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.

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