Patent ID: 8536903

Claim:
An output stage circuit for outputting a driving current varying with a process, the output stage circuit comprising: a first P-type metal-oxide-semiconductor transistor having a first terminal for receiving a first voltage, a second terminal, and a third terminal coupled to the second terminal, wherein a voltage of the third terminal is the first voltage minus a voltage drop between the first terminal and the second terminal of the first P-type metal-oxide-semiconductor transistor; a second P-type metal-oxide-semiconductor transistor having a first terminal for receiving the first voltage, a second terminal coupled to the third terminal of the first P-type metal-oxide-semiconductor transistor, and a third terminal for outputting an output voltage, wherein a voltage drop between the first terminal and the second terminal of the second P-type metal-oxide-semiconductor transistor is equal to the voltage drop between the first terminal and the second terminal of the first P-type metal-oxide-semiconductor transistor; an N-type metal-oxide-semiconductor transistor having a first terminal coupled to the third terminal of the first P-type metal-oxide-semiconductor transistor, a second terminal for receiving a kick signal, and a third terminal; and a current source coupled between the third terminal of the N-type metal-oxide-semiconductor transistor and ground for providing a constant current; wherein channel length of the first P-type metal-oxide-semiconductor transistor is equal to channel length of the second P-type metal-oxide-semiconductor transistor.