Question

Set an offset voltage for the op amp, otherwise there will not be an output from the PSpice simulation.

Problem4) Run a PSpice simulation of the 10 kHz "Phase-shift" oscillator of Prob. 1) in the last assignment (#8) as shown below. Plots of the output Vo(t) are required. Note: Here, a pair of 1N914 diodes D1,2 are incorporated to provide amplitude limiting of the oscillations Vo(t). taak C. O.A 6 loo о.А. mode( "Por Simulation a) Using a realistic Vos-1mV for the op amp, obtain a PSpice simulation for Volt)-showing the growth of oscillations to their steady-state sustained amplitude. Note : a time duration of 15 ms would suffice Compare for Voft) in a) with the corresponding theoretical predictions of: i) oscillations freauencv .i) estimated peak amplitude of the oscillations Volt). For the latter ,to estimate the amplitude, note the following regarding the resistor Rf which sets the Gain of the Transimpedance amplifier 1) Rf-120 k > Rf(min)- 110 k when the oscillations just begin to grow (D1,2 still OFF ). 2) Rf decreases to equal Rf(min)-110 k when the oscillations finally reach the steady-state sustained amplitude-thanks to a decrease in resistance of D1,2 when ON. Assume VD(on) -0.8V for the 1N914 diodes D1,2. b) c) Verify that indeed NO OSCILLATIONS can develop trigger is absent, l.e. Vos O. Document your results with plots of Volt). if : i) the 100k reduced to 50 k,or i) the oscillation

Answer 1

Problem4) Run a PSpice simulation of the 10 kHz "Phase-shift" oscillator of Prob. 1) in the last assignment (#8) as shown below. Plots of the output Vo(t) are required. Note: Here, a pair of 1N914 diodes D1,2 are incorporated to provide amplitude limiting of the oscillations Vo(t). taak C. O.A 6 loo о.А. mode( "Por Simulation a) Using a realistic Vos-1mV for the op amp, obtain a PSpice simulation for Volt)-showing the growth of oscillations to their steady-state sustained amplitude. Note : a time duration of 15 ms would suffice Compare for Voft) in a) with the corresponding theoretical predictions of: i) oscillations freauencv .i) estimated peak amplitude of the oscillations Volt). For the latter ,to estimate the amplitude, note the following regarding the resistor Rf which sets the Gain of the Transimpedance amplifier 1) Rf-120 k > Rf(min)- 110 k when the oscillations just begin to grow (D1,2 still OFF ). 2) Rf decreases to equal Rf(min)-110 k when the oscillations finally reach the steady-state sustained amplitude-thanks to a decrease in resistance of D1,2 when ON. Assume VD(on) -0.8V for the 1N914 diodes D1,2. b) c) Verify that indeed NO OSCILLATIONS can develop trigger is absent, l.e. Vos O. Document your results with plots of Volt). if : i) the 100k reduced to 50 k,or i) the oscillation