A diagnosis circuit comprises: a logic circuit, wherein the logic circuit comprises a set having a gate voltage terminal of an arm of a phase logical OR a dead time voltage terminal, and the set logical XOR a drain-source voltage terminal of another arm of the phase; a filter circuit coupled to the logic circuit, wherein the filter circuit is configured to filter transient noises; a comparison circuit coupled to the filter circuit, wherein the comparison circuit is configured to determine whether a phase current of a phase current terminal of the phase is greater than zero; and a latch coupled to the comparison circuit, wherein the latch is configured to store diagnosis signals temporarily.