VO = 12 V - 0.3 V = 11.7 V At first, it appears that the applied voltage will cause both diodes to be in the "on" state. However, if both are "on", the two voltages on the diodes will be different due to the different characteristics of the silicon and germanium diodes, while in parallel circuits the voltage is the same in theory. In fact, when applied voltage, a germanium diode having a voltage of 0.3 V will "turn on", trying to maintain its stability. This causes the silicon diode can not reach a voltage of 0.7, so the silicon diode can not be "on". So it can be said that the silicon diode is in an open circuit state.
