Re: circuit design
I think the resistor values are too low. Try with at least 1k, better 10kOhms.
Since the (+) input of the inverter and integrator is connected to ground, the input impedance of the inverter and integrator are just 100 Ohms.
So, if the input voltage is 5V, the current from the opamp outputs would be 50mA, well above the maximum current for general purpose opamps. The output current would be limited to something about 20mA, for a general purpose opamp, and distort the signal.
Also, specify what type of opamp you use. With a real opamp, the output voltage would increase to about Vcc or Vee. But for an ideal model the voltage may increase continously. Use a real opamp model.
With an integrator, if you apply a constant voltage at the input, the output voltage will increase in time - since it integrates it over time. The output voltage will be limited to about Vcc or Vee. Usually the integrator is initialized and used periodicaly, since it can integrate the offset and saturate.
Put a high resistor (1-10MOhms) in paralel with the capacitor to limit the gain at DC.
What is the role of the buffer here?