Amplifier

An amplifier, comprising:

• a first stage amplification circuit, comprising:
• a first transistor, having a first terminal, a second terminal and a control terminal, wherein the second terminal of the first transistor is configured to output a first amplified signal, and the control terminal of the first transistor is configured to receive a first input signal;
• a second transistor, having a first terminal, a second terminal and a control terminal, wherein the control terminal of the second transistor is configured to receive a first bias voltage;
• and
• a first voltage gap generation unit, coupled between the second terminal of the first transistor and the second terminal of the second transistor and configured to provide a voltage gap between a first terminal and a second terminal of the first voltage gap generation unit according to a current flowing through the first transistor and the second transistor;
• and
• a second stage amplification circuit, comprising:
• a third transistor, having a first terminal, a second terminal and a control terminal, wherein the first terminal of the third transistor is configured to receive a first voltage, and the second terminal of the third transistor is configured to output a first output signal;
• and
• a fourth transistor, having a first terminal, a second terminal and a control terminal, wherein the first terminal of the fourth transistor is configured to receive a second voltage, and the second terminal of the fourth transistor is coupled to the second terminal of the third transistor;
• wherein the control terminal of the third transistor and the control terminal of the fourth transistor is coupled between two different terminals of the first voltage gap generation unit.