Oscillation condition of the oscillation circuit
(1) Phase condition The oscillation circuit must have a feedback loop composed of an amplifier and a positive feedback network. It is necessary to ensure that the phase of the voltage fed back to the input of the amplifier circuit is in phase with the original input voltage, forming a positive feedback.
(2) Amplitude condition In order to maintain oscillation and stabilize the output, the voltage fed back to the input of the amplifier circuit must not be lower than the original input voltage.