Some embodiments of the present invention provide a conversion circuit for converting a current signal into a first output voltage signal, where the current signal flows through a sensing component. The conversion circuit includes: a first current eliminating circuit, configured to eliminate a first current in the current signal, the first current eliminating circuit including: a current sample and hold circuit； and a current driving circuit, coupled between the sensing component and the current sample and hold circuit； a second current eliminating circuit, coupled to the sensing component and configured to eliminate a second current in the current signal； and an integrating circuit, coupled to the sensing component and configured to integrating for a third current in the current signal, and output a first input voltage signal between a first integration output terminal and a second integration output terminal. According to some embodiments of the present invention, a background photoelectric current and a base current in the current signal may be eliminated, and integration may be carried out for a heartbeat current in the current signal by using the integrating circuit, such that the impacts caused by the background photoelectric current and the base current to the heartbeat current are removed, and the detection efficiency is improved.
