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Topic: N-Channel MOSFET with wide ohmic region (Read 483 times) previous topic - next topic


As my projects have become more involved, I have  branched out from just making digital circuits to interfacing to and designing analog circuits, but I am still a neophyte in analog.  At the moment,   I am trying to design an audio amplifier with automatic gain control, using an opamp peak detector output fed back to an N-channel MOSFET operating in the ohmic region.   I would prefer for this particular circuit a fairly wide ohmic region  (i.e., gate voltage excursion from turnoff to near saturation).   Using simulation,  I found a BSD214 N-channel MOSFET that has about 1.2 volts of gate voltage variation across the ohmic region,  but it is not readily available except in quantities, and in a SOT-23 package.  The other transistors I have simulated always show much narrower ohmic regions.

So, if anyone is familiar with an N-channel MOSFET with a 1 v. or more ohmic region, which is available in small quantities and in a standard thru-hole package, I'd sure appreciate a suggestion.

Thanks in advance for any help.

John Doner


Perhaps you want a transconductance opamp?
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