Patent ID: 8658958

Claim:
A light detecting circuit, comprising: a first resistor having a first end and a second end, and the second end of the first resistor coupled to a first voltage; a light sensor having a first end and a second end, and the second end of the light sensor coupled to the first voltage; a first current mirror having a master current end and a slave current end, the slave current end coupled to the first end of the first resistor, and the master current end coupled to the first end of the light sensor, wherein the first end of the first resistor is directly coupled to the slave current end of the first current mirror; and a current source coupled to the first end of the first resistor and the slave current end of the first current mirror, wherein the current source comprises: a second resistor having a first end and a second end, and the second end of the second resistor coupled to the first voltage; a second current mirror having a master current end and a slave current end, and the master current end of the second current mirror coupled to the first end of the second resistor; and a third current mirror having a master current end and a slave current end, the master current end of the third current mirror coupled to the slave current end of the second current mirror, and the slave current end of the third current mirror coupled to the first end of the first resistor, wherein a current flowing through the slave current end of the first current mirror is at least partly sank by the slave current end of the third current mirror in the current source.