FIGURE 4(a) shows the circuit of an oscillator and FIGURE 4(b) gives

the gain and phase response of the op-amp used.

When the circuit was simulated in PSpice using an ideal op-amp, the

circuit oscillated at the designed frequency. However when the ideal opamp

was replaced by the TL072 the frequency of oscillation was observed

to be about 15% lower.

Investigate this anomaly giving your answer in the form of a report of

about 750 words. The report should attempt an analysis of the circuit

and include the results of any PSpice simulations. You may wish to use

the transfer function derived as equation (6) in the appendix to lesson

3-1 to calculate the phase shift in the RC network.

So I am struggling with this question

I Have calculated the RC networks output to be 65kHz.

I can see from the bode plot that the OP has a phase shift of 90 deg at 65kHz

How can i work out the real frequency output?

I am aware that in order for the system to oscillate the loop feedback must be 360 deg at unity gain.

Any help on this would be appreciated I have also uploaded some images.

Thanks again.

the gain and phase response of the op-amp used.

When the circuit was simulated in PSpice using an ideal op-amp, the

circuit oscillated at the designed frequency. However when the ideal opamp

was replaced by the TL072 the frequency of oscillation was observed

to be about 15% lower.

Investigate this anomaly giving your answer in the form of a report of

about 750 words. The report should attempt an analysis of the circuit

and include the results of any PSpice simulations. You may wish to use

the transfer function derived as equation (6) in the appendix to lesson

3-1 to calculate the phase shift in the RC network.

So I am struggling with this question

I Have calculated the RC networks output to be 65kHz.

I can see from the bode plot that the OP has a phase shift of 90 deg at 65kHz

How can i work out the real frequency output?

I am aware that in order for the system to oscillate the loop feedback must be 360 deg at unity gain.

Any help on this would be appreciated I have also uploaded some images.

Thanks again.