Ultra-low working voltage rail-to-rail operational amplifier, and differential input amplification-stage circuit and output-stage circuit thereof

An ultra-low working voltage rail-to-rail operational amplifier, comprising:

• a differential input amplification-stage circuit, comprising:
• a voltage unit comprising a first voltage output end, a second voltage output end, and a third voltage output end,
• a first bulk-driven transistor and a second bulk-driven transistor configured to receive, respectively, the first input voltage and the second input voltage and convert, respectively, the first input voltage and the second input voltage into a first output current and a second output current, and wherein the first voltage output end is connected to the first bulk-driven transistor and to the second bulk-driven transistor and is configured to output a control voltage to the first bulk-driven transistor and the second bulk-driven transistor,
• a first mirror current source connected to the first bulk-driven transistor for receiving the first output current, a second mirror current source connected to the second bulk-driven transistor for receiving the second output current,
• a differential amplifier unit connected to the first and the third voltage output ends and configured for outputting a first adjustment current to the first mirror current source and outputting a second adjustment current to the second mirror current source in response to voltages output by the first and the third voltage output ends,
• wherein the first mirror current source and the second mirror current source are respectively connected to the second voltage output end and the third voltage output end,
• wherein the first mirror current source is configured to output a first predetermined current to the output-stage circuit according to the first output current and the first adjustment current, and
• wherein the second mirror current source is configured to output a second predetermined current to the output-stage circuit according to the second output current and the second adjustment current, for maintaining transconductance constancy of the differential input amplification-stage circuit;
• and
• an output-stage circuit connected to the differential input amplification-stage circuit, the output-stage circuit comprising:
• an amplifier unit configured to receive the first predetermined current and the second predetermined current from a differential input amplification-stage circuit, amplify the first predetermined current and the second predetermined current, and output a first amplified current and a second amplified current, and
• an output unit connected to the amplifier unit and configure to receive the first amplified current and the second amplified current, perform differencing and phase inversion on the first amplified current and the second amplified current, and convert the first amplified current and the second amplified current into an output voltage, so that the output voltage falls between a working voltage and zero volts.