Patent ID: 8823446

Claim:
A current source, for driving a Metal Oxide Semiconductor (MOS) circuit to generate a predetermined current, the current source comprising: a feedback circuit, comprising: a second MOS transistor, comprising: a first end, coupled to a voltage source; a control end; and a second end, coupled to the control end of the second MOS transistor; a third MOS transistor, comprising: a first end, coupled to the voltage source; a control end, coupled to the control end of the second MOS transistor; and a second end; a fourth MOS transistor, comprising: a first end, coupled to the second end of the third MOS transistor, for outputting a feedback voltage; a control end, for receiving a control voltage; and a second end; and a fifth MOS transistor, comprising: a first end, coupled to the second end of the second MOS transistor; a control end, for outputting an output voltage, wherein the output voltage is equal to the control voltage; and a second end; a first resistor, coupled between the ground end and the control end of the fifth MOS transistor; and the MOS circuit, comprising a plurality of MOS transistors connected in series; a first end of a sixth MOS transistor of the plurality of MOS transistors connected in series being coupled to the voltage source; a control end of each of the plurality of MOS transistors being directly coupled to the first end of the fourth MOS transistor, and controlled by the feedback voltage; and a second end of a seventh MOS transistor of the plurality of MOS transistors connected in series being coupled to the control end of the fifth MOS transistor; wherein the output voltage of the control end of the fifth MOS transistor is not influenced by series source/drain voltages of the plurality of MOS transistors, and a decrease of the feedback voltage is dependent on an equivalent channel length of the plurality of MOS transistors, not dependent on a process of the plurality of MOS transistors or a threshold voltage of the sixth MOS transistor.