Analytical Approach: In the combination of two Diode circuits at a time, only one Diode will turn ON. When V0 = + Vsat, then D1 is ON and D2 is OFF. When V0 = - Vsat then D2 is ON and D1 is OFF. So the given circuit introduces amplitude stabilization by preventing the Op-Amp from saturating and thus producing sinusoidal oscillations of fixed amplitude. Alternate Approach: The circuit shown is a Wein bridge oscillator. The amplitude of oscillations can be determined and stabilized by using a nonlinear control network. As the oscillations grow, the diodes start to conduct causing the effective resistance in the feedback to decrease. Equilibrium will be reached at the output amplitude that causes the loop gain to be exactly unity.