An overvoltage protection and gain bootstrap circuit of a power amplifier includes a power amplification transistor, and a diode reversely connected with a gate of the power amplification transistor. A negative electrode of the diode is connected with the gate of the power transistor, and a positive electrode of the diode is connected with a constant voltage source, such that a function of overvoltage protection and gain bootstrap of the circuit is realized by controlling a turn-on state of the diode. By adding a diode device to the circuit, gate-drain overvoltage protection for the power amplification transistor can be provided, and the gain of the amplifier can be improved before power compression, thereby improving linearity of the power amplifier. The structure of the circuit can be simple, with reduced occupied area hardware cost.

An overvoltage protection and gain bootstrap circuit of a power amplifier includes a power amplification transistor, and a diode reversely connected with a gate of the power amplification transistor. A negative electrode of the diode is connected with the gate of the power transistor, and a positive electrode of the diode is connected with a constant voltage source, such that a function of overvoltage protection and gain bootstrap of the circuit is realized by controlling a turn-on state of the diode. By adding a diode device to the circuit, gate-drain overvoltage protection for the power amplification transistor can be provided, and the gain of the amplifier can be improved before power compression, thereby improving linearity of the power amplifier. The structure of the circuit can be simple, with reduced occupied area hardware cost.

A switching power supply comprising: a control circuit which is provided at a primary side and controls a switching element based on a value which is fed back from a secondary side; a transformer; a secondary side rectifier element which rectifies voltage which is supplied from the transformer; and a secondary side smooth element which smoothes voltage which is rectified by the rectifier element, wherein voltage which is smoothed by the smooth element is supplied to an amplifier and voltage which is smoothed by the smooth element is fed back to the control circuit, further comprising: a diode which is connected between the smooth element and the amplifier in series.

A switching power supply comprising: a control circuit which is provided at a primary side and controls a switching element based on a value which is fed back from a secondary side; a transformer; a secondary side rectifier element which rectifies voltage which is supplied from the transformer; and a secondary side smooth element which smoothes voltage which is rectified by the rectifier element, wherein voltage which is smoothed by the smooth element is supplied to an amplifier and voltage which is smoothed by the smooth element is fed back to the control circuit, further comprising: a diode which is connected between the smooth element and the amplifier in series.