I have been studying and playing around with bipolar amps for a while and decided to learn more about MOS/FETS. The main reason I have stuck with bjts is the simplicity of there operation- always ~ +/-.6v Vbe. I can look at a circuit and figure out its operation and bias points without a data sheet for the transistor. Not so for MOS/FETS: six different types (Metal Oxide Semiconductor MOSFET Tutorial) and each type can have a range of threshold voltages!! The other problem, is that people on this forum (even in the Pass section and articles) who post ccts using these devices rarely say what type (depletion/enhancement) of devices they use (the MOSFET symbols used are often wrong) or there Vtreshold (other than the manufacturers number). And LTSpice dosnt help as they only have the enhancement mode symbol for there schematics (does this mean they only have enhancement mode models?). I have searched the net for a a while and found little info. I dont think I am alone in this confusion.
My questions:
are depletion mode MOSFETS ever used in audio? If not I need to ask no more questions. (but some how I doubt it).
in LTSpice, when picking different devices is there any way to know which MOSFET models are depletion, and even worse what there threshold (for FETS too) voltages are?
is there any more info on the web?
My questions:
are depletion mode MOSFETS ever used in audio? If not I need to ask no more questions. (but some how I doubt it).
in LTSpice, when picking different devices is there any way to know which MOSFET models are depletion, and even worse what there threshold (for FETS too) voltages are?
is there any more info on the web?
very few depletion mode mosfet are used - for one thing only N-ch can be made so no complements
the few available are often used just for CCS - some even in tube circuits
IXYS is making some very high V depletion mosfet that may interest ESL amp builders
a distinction to look for in enhancement mosfet is between Lateral and Vertical - with few Lateral being made but still considered superior for linear/audio
the few available are often used just for CCS - some even in tube circuits
IXYS is making some very high V depletion mosfet that may interest ESL amp builders
a distinction to look for in enhancement mosfet is between Lateral and Vertical - with few Lateral being made but still considered superior for linear/audio
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