Hello,

Here is a screenshot from the file:
View attachment 226183
Why do you use a mosfet?
How is the mosfet biased?

Bertus

Plz Solve my query I have to design 5khz frequency phase shift Oscillators N=4 tell meh ow to calculate Beta & design?

Mod: link to old Thread.
https://forum.allaboutcircuits.com/...rc-phase-shift-oscillator.175348/post-1583832

 

You need to bias the MOSFET so it is partially on with the feedback disconnected.

 

Since this is Homework, please post your best effort at doing this task so that we can give advice where needed.

 

calculate Beta

MOSFETs do not have Beta (current gain), they have transconductance (voltage to current gain).
BJT's have Beta.

 

Will you use the HUGE 30A Mosfet?

 

Since this is Homework, please post your best effort at doing this task so that we can give advice where needed.

Error in output waveform it got clipped and not symmetrical Frequency=5kHz

 

I have to design 5khz frequency phase shift Oscillators N=4

I don't see N=4 anywhere in your .asc simulation file?
In your assignment, is there any requirement for a particular waveform?

 

I don't see N=4 anywhere in your .asc simulation file?
In your assignment, is there any requirement for a particular waveform?

Here is N= 4 in feedback.... No requirement of wave but my wave got clipped when I changed values the symmetry disturbed of wave

 

This was my Circuit didn't you see N=4 here in feedback?

 

I can see four RC stages. Is that what you meant?

 

I can see four RC stages. Is that what you meant?

I run this circuit having 5 stages Frequency 5khz using 4 RC stage using attenuation O calculate Beta as 0.28 and then find gain using beta Which was 7 but After all that MOSFEt biasing my Circuit wave is not correct it got clipped in negative side also wavei is not uniform please run the circuit and find out error please

 

I run this circuit having 5 stages Frequency 5khz using 4 RC stage using attenuation O calculate Beta as 0.28 and then find gain using beta Which was 7 but After all that MOSFEt biasing my Circuit wave is not correct it got clipped in negative side also wavei is not uniform please run the circuit and find out error please

Sorry 4 Stages

 

Error in output waveform it got clipped and not symmetrical Frequency=5kHz

Hello there,

Are you really required to use a MOSFET in this design, or was that your first thought?

I ask because a MOSFET is very nonlinear, and although the gate signal may be a nearly perfect sine wave, the output cannot follow that sine wave because the MOSFET will have a nonlinear response to the gate voltage.
If you try to bias the MOSFET into a more linear operation you should get better results, but the long-term stability may still suffer.
The best way is probably with a resistor from drain to gate or something like that. You have to figure out the value such that you get linear operation, yet the gain is still good enough to allow the circuit to oscillate. Note that when you do this it may also take a longer time for the oscillator to start up.

 

Hello there,

Are you really required to use a MOSFET in this design, or was that your first thought?

I ask because a MOSFET is very nonlinear, and although the gate signal may be a nearly perfect sine wave, the output cannot follow that sine wave because the MOSFET will have a nonlinear response to the gate voltage.
If you try to bias the MOSFET into a more linear operation you should get better results, but the long-term stability may still suffer.
The best way is probably with a resistor from drain to gate or something like that. You have to figure out the value such that you get linear operation, yet the gain is still good enough to allow the circuit to oscillate. Note that when you do this it may also take a longer time for the oscillator to start up.

Yes I have to use MOSFET only as it is assigned to me ...but I tried my best but still output waveform got clipped or either symmetry disturbed when I biased the MOSFET any solution for it plz check my above circuit

 

No requirement of wave

In that case a clipped waveform is acceptable. Just adjust component values to reduce the present ~12kHz frequency to the specified 5kHz.

 

In that case a clipped waveform is acceptable. Just adjust component values to reduce the present ~12kHz frequency to the specified 5kHz.

I have adjusted it for 5khz?? 12khz what'?

 

The sim in post #9 generates pulses with a repetition frequency of ~12.7kHz. It does not generate a sine-wave, if that's what you are expecting. Your assignment apparently does not call for a sine-wave.

 

I ha

The sim in post #9 generates pulses with a repetition frequency of ~12.7kHz. It does not generate a sine-wave, if that's what you are expecting. Your assignment apparently does not call for a sine-wave.

RC phase shift produces sine wave right? And I have to make 5khz fruqeucny Waveform how to tackle it plz make necessary adjustments in it

 

I ha
RC phase shift produces sine wave right? And I have to make 5khz fruqeucny Waveform how to tackle it plz make necessary adjustments in it

Make necessary adjustments in my cir unit in ltspice to make it 5khz and send it again ... Thank you

 

Make necessary adjustments in my cir unit in ltspice to make it 5khz and send it again ... Thank you

It’s your homework. Not ours. Try jto do it yourself.