really don't know why can't get this simple task done

Someone kindly assist. Trying to replace the JFET with a MOSFET as title says, to still get oscillation

Thanks

 

hi Z,
In order to get assistance, you have to tell us what is the problem.
Your asc circuit has disconnected components, also where is the test point for the Output signal.

Post your 'oscillation' images and plots.
E

 

hi,
When the unused components are removed, it runs in simulation.
E
Using a PFET

 

Thanks E

But i am trying to accomplish same stuff with MOSFET

With no diode (D3) at the output.

Output is output of 2nd op amp

 

Output is output of 2nd op amp

?? There's only one opamp. Did you post the right schematic?

 

?? There's only one opamp. Did you post the right schematic?

My fault..Only one op amp

The output is output of op amp

 

hi Z,
Check out this link.
E
https://electronics.stackexchange.com/questions/176411/depletion-mode-p-channel-mosfet-availability

 

Hmmm..So no depletion PMOS

Thanks..That's what TS needed
Guess there was something to learn in the class he missed on MOSFET

Thanks

 

hi Z,
Why not just use a jFET.?
E

 

Someone kindly assist. Trying to replace the JFET with a MOSFET as title says

Thank you for using something more descriptive than FET. There are many kinds of FETs, but not all FETs are MOSFETs or JFETs; and MOSFETs generally can't be used in place of JFETs. Sloppy descriptions lead to confusion.

A JFET is on with no gate bias and an N channel JFET requires a negative Vgs to turn it off.

A depletion mode N channel MOSFET will also be on with zero gate bias, but you can turn it on harder with a positive Vgs. Enhancement mode are much more common than depletion mode. Sadly, the symbol used for enhancement mode MOSFETs has a dashed line that most of us don't use when we draw schematics by hand:

In my 3 decades of working with memory/microprocessor designs, no one drew (by hand) enhancement mode MOSFETs with a dashed line. Which further adds confusion...

In NMOS only designs, favored back when CMOS was slower, they used a depletion mode device for the load resistor.

 

And you can always use the original depletion devices: vacuum tubes!

 

Here you go:-