A signal conversion circuit, a heart rate sensor, and an electronic device are provided, and the signal conversion circuit includes: a photoelectric conversion circuit, configured to convert an optical signal into a current signal; a differential signal conversion circuit, connected to the photoelectric conversion circuit, and configured to convert the current signal into a first differential signal and a second differential signal, where the first differential signal is an integration signal of the current signal in a first phase, and the second differential signal is an integration signal of the current signal in a second phase; and a subtraction amplifier, connected to the differential signal conversion circuit, and configured to amplify a difference value between the first differential signal and the second differential signal, to generate a third differential signal. The signal conversion circuit of embodiments of the present disclosure can effectively suppress ambient interference.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type: and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type: and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

An amplifier includes an input transistor, an input terminal, a first current source, a cascode transistor, and a second current source. The input transistor is coupled to the input terminal. The first current source is coupled to the input transistor and is configured to provide a bias current to the input transistor that is proportional to absolute temperature. The cascode transistor is coupled to the input transistor. The second current source is coupled to the cascode transistor and is configured to provide a bias current to the cascode transistor that is complementary to absolute temperature.

Differential amplifier circuitry including: first and second main transistors of a given conductivity type; and first and second auxiliary transistors of an opposite conductivity type, where the first and second main transistors are connected along first and second main current paths passing between first and second main voltage reference nodes and first and second output nodes, respectively, with their source terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by component input signals of a differential input signal; and the first and second auxiliary transistors are connected along first and second auxiliary current paths passing between first and second auxiliary voltage reference nodes and the first and second output nodes, respectively, with their drain terminals connected to the first and second output nodes, respectively, and with their gate terminals controlled by the component input signals of the differential input signal.

An amplifier includes an input transistor, an input terminal, a first current source, a cascode transistor, and a second current source. The input transistor is coupled to the input terminal. The first current source is coupled to the input transistor and is configured to provide a bias current to the input transistor that is proportional to absolute temperature. The cascode transistor is coupled to the input transistor. The second current source is coupled to the cascode transistor and is configured to provide a bias current to the cascode transistor that is complementary to absolute temperature.

A signal conversion circuit, a heart rate sensor, and an electronic device are provided, and the signal conversion circuit includes: a photoelectric conversion circuit, configured to convert an optical signal into a current signal; a differential signal conversion circuit, connected to the photoelectric conversion circuit, and configured to convert the current signal into a first differential signal and a second differential signal, where the first differential signal is an integration signal of the current signal in a first phase, and the second differential signal is an integration signal of the current signal in a second phase; and a subtraction amplifier, connected to the differential signal conversion circuit, and configured to amplify a difference value between the first differential signal and the second differential signal, to generate a third differential signal. The signal conversion circuit of embodiments of the present disclosure can effectively suppress ambient interference.